Publications by authors named "Hermine E Veenstra-Knol"

31 Publications

Genotype-phenotype correlation at codon 1740 of SETD2.

Am J Med Genet A 2020 09 24;182(9):2037-2048. Epub 2020 Jul 24.

Clinical Genetic Services, Department of Pediatrics, NYU School of Medicine, New York, New York, USA.

The SET domain containing 2, histone lysine methyltransferase encoded by SETD2 is a dual-function methyltransferase for histones and microtubules and plays an important role for transcriptional regulation, genomic stability, and cytoskeletal functions. Specifically, SETD2 is associated with trimethylation of histone H3 at lysine 36 (H3K36me3) and methylation of α-tubulin at lysine 40. Heterozygous loss of function and missense variants have previously been described with Luscan-Lumish syndrome (LLS), which is characterized by overgrowth, neurodevelopmental features, and absence of overt congenital anomalies. We have identified 15 individuals with de novo variants in codon 1740 of SETD2 whose features differ from those with LLS. Group 1 consists of 12 individuals with heterozygous variant c.5218C>T p.(Arg1740Trp) and Group 2 consists of 3 individuals with heterozygous variant c.5219G>A p.(Arg1740Gln). The phenotype of Group 1 includes microcephaly, profound intellectual disability, congenital anomalies affecting several organ systems, and similar facial features. Individuals in Group 2 had moderate to severe intellectual disability, low normal head circumference, and absence of additional major congenital anomalies. While LLS is likely due to loss of function of SETD2, the clinical features seen in individuals with variants affecting codon 1740 are more severe suggesting an alternative mechanism, such as gain of function, effects on epigenetic regulation, or posttranslational modification of the cytoskeleton. Our report is a prime example of different mutations in the same gene causing diverging phenotypes and the features observed in Group 1 suggest a new clinically recognizable syndrome uniquely associated with the heterozygous variant c.5218C>T p.(Arg1740Trp) in SETD2.
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http://dx.doi.org/10.1002/ajmg.a.61724DOI Listing
September 2020

De novo variants in CAMTA1 cause a syndrome variably associated with spasticity, ataxia, and intellectual disability.

Eur J Hum Genet 2020 06 10;28(6):763-769. Epub 2020 Mar 10.

Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.

Previously, intragenic CAMTA1 copy number variants (CNVs) have been shown to cause non-progressive, congenital ataxia with or without intellectual disability (OMIM#614756). However, ataxia, intellectual disability, and dysmorphic features were all incompletely penetrant, even within families. Here, we describe four patients with de novo nonsense, frameshift or missense CAMTA1 variants. All four patients predominantly manifested features of ataxia and/or spasticity. Borderline intellectual disability and dysmorphic features were both present in one patient only, and other neurological and behavioural symptoms were variably present. Neurodevelopmental delay was found to be mild. Our findings indicate that also nonsense, frameshift and missense variants in CAMTA1 can cause a spastic ataxia syndrome as the main phenotype.
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http://dx.doi.org/10.1038/s41431-020-0600-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7253440PMC
June 2020

Correction: The ARID1B spectrum in 143 patients: from nonsyndromic intellectual disability to Coffin-Siris syndrome.

Authors:
Pleuntje J van der Sluijs Sandra Jansen Samantha A Vergano Miho Adachi-Fukuda Yasemin Alanay Adila AlKindy Anwar Baban Allan Bayat Stefanie Beck-Wödl Katherine Berry Emilia K Bijlsma Levinus A Bok Alwin F J Brouwer Ineke van der Burgt Philippe M Campeau Natalie Canham Krystyna Chrzanowska Yoyo W Y Chu Brain H Y Chung Karin Dahan Marjan De Rademaeker Anne Destree Tracy Dudding-Byth Rachel Earl Nursel Elcioglu Ellen R Elias Christina Fagerberg Alice Gardham Blanca Gener Erica H Gerkes Ute Grasshoff Arie van Haeringen Karin R Heitink Johanna C Herkert Nicolette S den Hollander Denise Horn David Hunt Sarina G Kant Mitsuhiro Kato Hülya Kayserili Rogier Kersseboom Esra Kilic Malgorzata Krajewska-Walasek Kylin Lammers Lone W Laulund Damien Lederer Melissa Lees Vanesa López-González Saskia Maas Grazia M S Mancini Carlo Marcelis Francisco Martinez Isabelle Maystadt Marianne McGuire Shane McKee Sarju Mehta Kay Metcalfe Jeff Milunsky Seiji Mizuno John B Moeschler Christian Netzer Charlotte W Ockeloen Barbara Oehl-Jaschkowitz Nobuhiko Okamoto Sharon N M Olminkhof Carmen Orellana Laurent Pasquier Caroline Pottinger Vera Riehmer Stephen P Robertson Maian Roifman Caroline Rooryck Fabienne G Ropers Monica Rosello Claudia A L Ruivenkamp Mahmut S Sagiroglu Suzanne C E H Sallevelt Amparo Sanchis Calvo Pelin O Simsek-Kiper Gabriela Soares Lucia Solaeche Fatma Mujgan Sonmez Miranda Splitt Duco Steenbeek Alexander P A Stegmann Constance T R M Stumpel Saori Tanabe Eyyup Uctepe G Eda Utine Hermine E Veenstra-Knol Sunita Venkateswaran Catheline Vilain Catherine Vincent-Delorme Anneke T Vulto-van Silfhout Patricia Wheeler Golder N Wilson Louise C Wilson Bernd Wollnik Tomoki Kosho Dagmar Wieczorek Evan Eichler Rolph Pfundt Bert B A de Vries Jill Clayton-Smith Gijs W E Santen

Genet Med 2019 Sep;21(9):2160-2161

Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands.

The original version of this Article contained an error in the spelling of the author Pleuntje J. van der Sluijs, which was incorrectly given as Eline (P. J.) van der Sluijs. This has now been corrected in both the PDF and HTML versions of the Article.
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http://dx.doi.org/10.1038/s41436-018-0368-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6752317PMC
September 2019

The ARID1B spectrum in 143 patients: from nonsyndromic intellectual disability to Coffin-Siris syndrome.

Authors:
Pleuntje J van der Sluijs Sandra Jansen Samantha A Vergano Miho Adachi-Fukuda Yasemin Alanay Adila AlKindy Anwar Baban Allan Bayat Stefanie Beck-Wödl Katherine Berry Emilia K Bijlsma Levinus A Bok Alwin F J Brouwer Ineke van der Burgt Philippe M Campeau Natalie Canham Krystyna Chrzanowska Yoyo W Y Chu Brain H Y Chung Karin Dahan Marjan De Rademaeker Anne Destree Tracy Dudding-Byth Rachel Earl Nursel Elcioglu Ellen R Elias Christina Fagerberg Alice Gardham Blanca Gener Erica H Gerkes Ute Grasshoff Arie van Haeringen Karin R Heitink Johanna C Herkert Nicolette S den Hollander Denise Horn David Hunt Sarina G Kant Mitsuhiro Kato Hülya Kayserili Rogier Kersseboom Esra Kilic Malgorzata Krajewska-Walasek Kylin Lammers Lone W Laulund Damien Lederer Melissa Lees Vanesa López-González Saskia Maas Grazia M S Mancini Carlo Marcelis Francisco Martinez Isabelle Maystadt Marianne McGuire Shane McKee Sarju Mehta Kay Metcalfe Jeff Milunsky Seiji Mizuno John B Moeschler Christian Netzer Charlotte W Ockeloen Barbara Oehl-Jaschkowitz Nobuhiko Okamoto Sharon N M Olminkhof Carmen Orellana Laurent Pasquier Caroline Pottinger Vera Riehmer Stephen P Robertson Maian Roifman Caroline Rooryck Fabienne G Ropers Monica Rosello Claudia A L Ruivenkamp Mahmut S Sagiroglu Suzanne C E H Sallevelt Amparo Sanchis Calvo Pelin O Simsek-Kiper Gabriela Soares Lucia Solaeche Fatma Mujgan Sonmez Miranda Splitt Duco Steenbeek Alexander P A Stegmann Constance T R M Stumpel Saori Tanabe Eyyup Uctepe G Eda Utine Hermine E Veenstra-Knol Sunita Venkateswaran Catheline Vilain Catherine Vincent-Delorme Anneke T Vulto-van Silfhout Patricia Wheeler Golder N Wilson Louise C Wilson Bernd Wollnik Tomoki Kosho Dagmar Wieczorek Evan Eichler Rolph Pfundt Bert B A de Vries Jill Clayton-Smith Gijs W E Santen

Genet Med 2019 06 8;21(6):1295-1307. Epub 2018 Nov 8.

Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands.

Purpose: Pathogenic variants in ARID1B are one of the most frequent causes of intellectual disability (ID) as determined by large-scale exome sequencing studies. Most studies published thus far describe clinically diagnosed Coffin-Siris patients (ARID1B-CSS) and it is unclear whether these data are representative for patients identified through sequencing of unbiased ID cohorts (ARID1B-ID). We therefore sought to determine genotypic and phenotypic differences between ARID1B-ID and ARID1B-CSS. In parallel, we investigated the effect of different methods of phenotype reporting.

Methods: Clinicians entered clinical data in an extensive web-based survey.

Results: 79 ARID1B-CSS and 64 ARID1B-ID patients were included. CSS-associated dysmorphic features, such as thick eyebrows, long eyelashes, thick alae nasi, long and/or broad philtrum, small nails and small or absent fifth distal phalanx and hypertrichosis, were observed significantly more often (p < 0.001) in ARID1B-CSS patients. No other significant differences were identified.

Conclusion: There are only minor differences between ARID1B-ID and ARID1B-CSS patients. ARID1B-related disorders seem to consist of a spectrum, and patients should be managed similarly. We demonstrated that data collection methods without an explicit option to report the absence of a feature (such as most Human Phenotype Ontology-based methods) tended to underestimate gene-related features.
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http://dx.doi.org/10.1038/s41436-018-0330-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6752273PMC
June 2019

NBEA: Developmental disease gene with early generalized epilepsy phenotypes.

Ann Neurol 2018 11 25;84(5):788-795. Epub 2018 Oct 25.

Columbia University Medical Center, Institute for Genomic Medicine, New York, NY.

NBEA is a candidate gene for autism, and de novo variants have been reported in neurodevelopmental disease (NDD) cohorts. However, NBEA has not been rigorously evaluated as a disease gene, and associated phenotypes have not been delineated. We identified 24 de novo NBEA variants in patients with NDD, establishing NBEA as an NDD gene. Most patients had epilepsy with onset in the first few years of life, often characterized by generalized seizure types, including myoclonic and atonic seizures. Our data show a broader phenotypic spectrum than previously described, including a myoclonic-astatic epilepsy-like phenotype in a subset of patients. Ann Neurol 2018;84:796-803.
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http://dx.doi.org/10.1002/ana.25350DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6249120PMC
November 2018

The Tatton-Brown-Rahman Syndrome: A clinical study of 55 individuals with constitutive variants.

Wellcome Open Res 2018 23;3:46. Epub 2018 Apr 23.

Division of Genetics and Epidemiology, Institute of Cancer Research, London, UK.

Tatton-Brown-Rahman syndrome (TBRS; OMIM 615879), also known as the DNMT3A-overgrowth syndrome, is an overgrowth intellectual disability syndrome first described in 2014 with a report of 13 individuals with constitutive heterozygous variants. Here we have undertaken a detailed clinical study of 55 individuals with variants, including the 13 previously reported individuals. An intellectual disability and overgrowth were reported in >80% of individuals with TBRS and were designated major clinical associations. Additional frequent clinical associations (reported in 20-80% individuals) included an evolving facial appearance with low-set, heavy, horizontal eyebrows and prominent upper central incisors; joint hypermobility (74%); obesity (weight ³2SD, 67%); hypotonia (54%); behavioural/psychiatric issues (most frequently autistic spectrum disorder, 51%); kyphoscoliosis (33%) and afebrile seizures (22%). One individual was diagnosed with acute myeloid leukaemia in teenage years. Based upon the results from this study, we present our current management for individuals with TBRS.
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http://dx.doi.org/10.12688/wellcomeopenres.14430.1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5964628PMC
April 2018

Recessive Spondylocarpotarsal Synostosis Syndrome Due to Compound Heterozygosity for Variants in MYH3.

Am J Hum Genet 2018 06 24;102(6):1115-1125. Epub 2018 May 24.

Department of Women's and Children's Health, Dunedin School of Medicine, University of Otago, Dunedin 9054, New Zealand. Electronic address:

Spondylocarpotarsal synostosis syndrome (SCTS) is characterized by intervertebral fusions and fusion of the carpal and tarsal bones. Biallelic mutations in FLNB cause this condition in some families, whereas monoallelic variants in MYH3, encoding embryonic heavy chain myosin 3, have been implicated in dominantly inherited forms of the disorder. Here, five individuals without FLNB mutations from three families were hypothesized to be affected by recessive SCTS on account of sibling recurrence of the phenotype. Initial whole-exome sequencing (WES) showed that all five were heterozygous for one of two independent splice-site variants in MYH3. Despite evidence indicating that three of the five individuals shared two allelic haplotypes encompassing MYH3, no second variant could be located in the WES datasets. Subsequent genome sequencing of these three individuals demonstrated a variant altering a 5' UTR splice donor site (rs557849165 in MYH3) not represented by exome-capture platforms. When the cohort was expanded to 16 SCTS-affected individuals without FLNB mutations, nine had truncating mutations transmitted by unaffected parents, and six inherited the rs557849165 variant in trans, an observation at odds with the population allele frequency for this variant. The rs557849165 variant disrupts splicing in the 5' UTR but is still permissive of MYH3 translational initiation, albeit with reduced efficiency. Although some MYH3 variants cause dominant SCTS, these data indicate that others (notably truncating variants) do not, except in the context of compound heterozygosity for a second hypomorphic allele. These observations make genetic diagnosis challenging in the context of simplex presentations of the disorder.
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http://dx.doi.org/10.1016/j.ajhg.2018.04.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5992117PMC
June 2018

mosaicism in apparently unaffected parents is associated with autism spectrum disorder and neurocognitive dysfunction.

Mol Autism 2018 25;9. Epub 2018 Jan 25.

2Donders Institute for Brain, Cognition and Behavior, Centre for Neuroscience, Radboud University, Nijmegen, the Netherlands.

Background: Genetic mosaicism is only detected occasionally when there are no obvious health or developmental issues. Most cases concern healthy parents in whom mosaicism is identified upon targeted testing of a genetic defect that was initially detected in their children. A germline genetic defect affecting the euchromatin histone methyltransferase 1 () gene causes Kleefstra syndrome, which is associated with the typical triad of distinct facial appearance, (childhood) hypotonia, and intellectual disability. A high degree of psychopathology is associated with this syndrome. A few parents with a mosaic mutation have been detected upon testing after a child was diagnosed with a germline defect. At first glance, carriers of a mosaic mutation appeared to function normally. However, recent studies have shown that de novo, postzygotic mutations in important developmental genes significantly contribute to autism spectrum disorder (ASD). Therefore, we hypothesized that mosaicism could cause neuropsychiatric defects. To investigate this, we performed a detailed investigation of cognitive neuropsychiatric parameters in parents identified with mosaicism.

Methods: Three adults (two males, one female) with a genetically confirmed diagnosis of mosaicism were examined by means of a battery of tests and observational instruments covering both neurocognitive and psychiatric features. The battery included the following instruments: the Autism Diagnostic Observation Schedule (ADOS), the mini Psychiatric Assessment Schedules for Adults with Developmental Disabilities (mini PAS-ADD), the Vineland Adaptive Behavior Scales (VABS), and the Cambridge Neuropsychological Test Automated Battery (CANTAB). These measures were compared with our previously reported data from Kleefstra syndrome patients with confirmed (germline) defects.

Results: All three subjects achieved maximum total scores on the VABS, indicative of adequate (adaptive) functioning. In all, scores above cutoff were found on the ADOS for ASD and on the mini PAS-ADD for major depressive disorder (lifetime). Finally, results on the CANTAB showed impaired cognitive flexibility in all subjects.

Conclusion: Individuals with mosaicism seem to have increased vulnerability for developing severe psychopathology, especially ASD and mood disorders. Although at first glance they appear to be well-adapted in their daily functioning, they may experience significant psychiatric symptoms and show reduced cognitive flexibility in comparison to the general population.
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http://dx.doi.org/10.1186/s13229-018-0193-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5784506PMC
October 2018

Biallelic variants in WARS2 encoding mitochondrial tryptophanyl-tRNA synthase in six individuals with mitochondrial encephalopathy.

Hum Mutat 2017 12 6;38(12):1786-1795. Epub 2017 Oct 6.

Department of Pediatrics, Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.

Mitochondrial protein synthesis involves an intricate interplay between mitochondrial DNA encoded RNAs and nuclear DNA encoded proteins, such as ribosomal proteins and aminoacyl-tRNA synthases. Eukaryotic cells contain 17 mitochondria-specific aminoacyl-tRNA synthases. WARS2 encodes mitochondrial tryptophanyl-tRNA synthase (mtTrpRS), a homodimeric class Ic enzyme (mitochondrial tryptophan-tRNA ligase; EC 6.1.1.2). Here, we report six individuals from five families presenting with either severe neonatal onset lactic acidosis, encephalomyopathy and early death or a later onset, more attenuated course of disease with predominating intellectual disability. Respiratory chain enzymes were usually normal in muscle and fibroblasts, while a severe combined respiratory chain deficiency was found in the liver of a severely affected individual. Exome sequencing revealed rare biallelic variants in WARS2 in all affected individuals. An increase of uncharged mitochondrial tRNA and a decrease of mtTrpRS protein content were found in fibroblasts of affected individuals. We hereby define the clinical, neuroradiological, and metabolic phenotype of WARS2 defects. This confidently implicates that mutations in WARS2 cause mitochondrial disease with a broad spectrum of clinical presentation.
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http://dx.doi.org/10.1002/humu.23340DOI Listing
December 2017

Autosomal dominant frontometaphyseal dysplasia: Delineation of the clinical phenotype.

Am J Med Genet A 2017 Jul 12;173(7):1739-1746. Epub 2017 May 12.

Department of Women's and Children's Health, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand.

Frontometaphyseal dysplasia (FMD) is caused by gain-of-function mutations in the X-linked gene FLNA in approximately 50% of patients. Recently we characterized an autosomal dominant form of FMD (AD-FMD) caused by mutations in MAP3K7, which accounts for the condition in the majority of patients who lack a FLNA mutation. We previously also described a patient with a de novo variant in TAB2, which we hypothesized was causative of another form of AD-FMD. In this study, a cohort of 20 individuals with AD-FMD is clinically evaluated. This cohort consists of 15 individuals with the recently described, recurrent mutation (c.1454C>T) in MAP3K7, as well as three individuals with missense mutations that result in substitutions in the N-terminal kinase domain of TGFβ-activated kinase 1 (TAK1), encoded by MAP3K7. Additionally, two individuals have missense variants in the gene TAB2, which encodes a protein with a close functional relationship to TAK1, TAK1-associated binding protein 2 (TAB2). Although the X-linked and autosomal dominant forms of FMD are very similar, there are distinctions to be made between the two conditions. Individuals with AD-FMD have characteristic facial features, and are more likely to be deaf, have scoliosis and cervical fusions, and have a cleft palate. Furthermore, there are features only found in AD-FMD in our review of the literature including valgus deformity of the feet and predisposition to keloid scarring. Finally, intellectual disability is present in a small number of subjects with AD-FMD but has not been described in association with X-linked FMD.
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http://dx.doi.org/10.1002/ajmg.a.38267DOI Listing
July 2017

Heterozygous HNRNPU variants cause early onset epilepsy and severe intellectual disability.

Hum Genet 2017 07 9;136(7):821-834. Epub 2017 Apr 9.

Institut für Humangenetik, Universitätsklinikum Essen, Universität Duisburg-Essen, Hufelandstr. 55, 45122, Essen, Germany.

Pathogenic variants in genes encoding subunits of the spliceosome are the cause of several human diseases, such as neurodegenerative diseases. The RNA splicing process is facilitated by the spliceosome, a large RNA-protein complex consisting of small nuclear ribonucleoproteins (snRNPs), and many other proteins, such as heterogeneous nuclear ribonucleoproteins (hnRNPs). The HNRNPU gene (OMIM *602869) encodes the heterogeneous nuclear ribonucleoprotein U, which plays a crucial role in mammalian development. HNRNPU is expressed in the fetal brain and adult heart, kidney, liver, brain, and cerebellum. Microdeletions in the 1q44 region encompassing HNRNPU have been described in patients with intellectual disability (ID) and other clinical features, such as seizures, corpus callosum abnormalities (CCA), and microcephaly. Recently, pathogenic HNRNPU variants were identified in large ID and epileptic encephalopathy cohorts. In this study, we provide detailed clinical information of five novels and review two of the previously published individuals with (likely) pathogenic de novo variants in the HNRNPU gene including three non-sense and two missense variants, one small intragenic deletion, and one duplication. The phenotype in individuals with variants in HNRNPU is characterized by early onset seizures (6/7), severe ID (6/6), severe speech impairment (6/6), hypotonia (6/7), and central nervous system (CNS) (5/6), cardiac (4/6), and renal abnormalities (3/4). In this study, we broaden the clinical and mutational HNRNPU-associated spectrum, and demonstrate that heterozygous HNRNPU variants cause epilepsy, severe ID with striking speech impairment and variable CNS, cardiac, and renal anomalies.
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http://dx.doi.org/10.1007/s00439-017-1795-6DOI Listing
July 2017

Haploinsufficiency of MeCP2-interacting transcriptional co-repressor SIN3A causes mild intellectual disability by affecting the development of cortical integrity.

Nat Genet 2016 08 11;48(8):877-87. Epub 2016 Jul 11.

Department of Molecular Animal Physiology, Donders Institute for Brain, Cognition and Behavior, Radboud University, Nijmegen, the Netherlands.

Numerous genes are associated with neurodevelopmental disorders such as intellectual disability and autism spectrum disorder (ASD), but their dysfunction is often poorly characterized. Here we identified dominant mutations in the gene encoding the transcriptional repressor and MeCP2 interactor switch-insensitive 3 family member A (SIN3A; chromosome 15q24.2) in individuals who, in addition to mild intellectual disability and ASD, share striking features, including facial dysmorphisms, microcephaly and short stature. This phenotype is highly related to that of individuals with atypical 15q24 microdeletions, linking SIN3A to this microdeletion syndrome. Brain magnetic resonance imaging showed subtle abnormalities, including corpus callosum hypoplasia and ventriculomegaly. Intriguingly, in vivo functional knockdown of Sin3a led to reduced cortical neurogenesis, altered neuronal identity and aberrant corticocortical projections in the developing mouse brain. Together, our data establish that haploinsufficiency of SIN3A is associated with mild syndromic intellectual disability and that SIN3A can be considered to be a key transcriptional regulator of cortical brain development.
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http://dx.doi.org/10.1038/ng.3619DOI Listing
August 2016

Whole-exome sequencing is a powerful approach for establishing the etiological diagnosis in patients with intellectual disability and microcephaly.

BMC Med Genomics 2016 Feb 4;9. Epub 2016 Feb 4.

Department of Genetics, University of Groningen, University Medical Centre Groningen, P.O. Box 30.001, 9700 RB, Groningen, The Netherlands.

Background: Clinical and genetic heterogeneity in monogenetic disorders represents a major diagnostic challenge. Although the presence of particular clinical features may aid in identifying a specific cause in some cases, the majority of patients remain undiagnosed. Here, we investigated the utility of whole-exome sequencing as a diagnostic approach for establishing a molecular diagnosis in a highly heterogeneous group of patients with varied intellectual disability and microcephaly.

Methods: Whole-exome sequencing was performed in 38 patients, including three sib-pairs, in addition to or in parallel with genetic analyses that were performed during the diagnostic work-up of the study participants.

Results: In ten out of these 35 families (29 %), we found mutations in genes already known to be related to a disorder in which microcephaly is a main feature. Two unrelated patients had mutations in the ASPM gene. In seven other patients we found mutations in RAB3GAP1, RNASEH2B, KIF11, ERCC8, CASK, DYRK1A and BRCA2. In one of the sib-pairs, mutations were found in the RTTN gene. Mutations were present in seven out of our ten families with an established etiological diagnosis with recessive inheritance.

Conclusions: We demonstrate that whole-exome sequencing is a powerful tool for the diagnostic evaluation of patients with highly heterogeneous neurodevelopmental disorders such as intellectual disability with microcephaly. Our results confirm that autosomal recessive disorders are highly prevalent among patients with microcephaly.
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http://dx.doi.org/10.1186/s12920-016-0167-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4743197PMC
February 2016

De Novo Loss-of-Function Mutations in USP9X Cause a Female-Specific Recognizable Syndrome with Developmental Delay and Congenital Malformations.

Am J Hum Genet 2016 Feb 28;98(2):373-81. Epub 2016 Jan 28.

Department of Human Genetics, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands. Electronic address:

Mutations in more than a hundred genes have been reported to cause X-linked recessive intellectual disability (ID) mainly in males. In contrast, the number of identified X-linked genes in which de novo mutations specifically cause ID in females is limited. Here, we report 17 females with de novo loss-of-function mutations in USP9X, encoding a highly conserved deubiquitinating enzyme. The females in our study have a specific phenotype that includes ID/developmental delay (DD), characteristic facial features, short stature, and distinct congenital malformations comprising choanal atresia, anal abnormalities, post-axial polydactyly, heart defects, hypomastia, cleft palate/bifid uvula, progressive scoliosis, and structural brain abnormalities. Four females from our cohort were identified by targeted genetic testing because their phenotype was suggestive for USP9X mutations. In several females, pigment changes along Blaschko lines and body asymmetry were observed, which is probably related to differential (escape from) X-inactivation between tissues. Expression studies on both mRNA and protein level in affected-female-derived fibroblasts showed significant reduction of USP9X level, confirming the loss-of-function effect of the identified mutations. Given that some features of affected females are also reported in known ciliopathy syndromes, we examined the role of USP9X in the primary cilium and found that endogenous USP9X localizes along the length of the ciliary axoneme, indicating that its loss of function could indeed disrupt cilium-regulated processes. Absence of dysregulated ciliary parameters in affected female-derived fibroblasts, however, points toward spatiotemporal specificity of ciliary USP9X (dys-)function.
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http://dx.doi.org/10.1016/j.ajhg.2015.12.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4746365PMC
February 2016

The Koolen-de Vries syndrome: a phenotypic comparison of patients with a 17q21.31 microdeletion versus a KANSL1 sequence variant.

Eur J Hum Genet 2016 May 26;24(5):652-9. Epub 2015 Aug 26.

Department of Human Genetics, Radboud Institute for Molecular Life Sciences and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands.

The Koolen-de Vries syndrome (KdVS; OMIM #610443), also known as the 17q21.31 microdeletion syndrome, is a clinically heterogeneous disorder characterised by (neonatal) hypotonia, developmental delay, moderate intellectual disability, and characteristic facial dysmorphism. Expressive language development is particularly impaired compared with receptive language or motor skills. Other frequently reported features include social and friendly behaviour, epilepsy, musculoskeletal anomalies, congenital heart defects, urogenital malformations, and ectodermal anomalies. The syndrome is caused by a truncating variant in the KAT8 regulatory NSL complex unit 1 (KANSL1) gene or by a 17q21.31 microdeletion encompassing KANSL1. Herein we describe a novel cohort of 45 individuals with KdVS of whom 33 have a 17q21.31 microdeletion and 12 a single-nucleotide variant (SNV) in KANSL1 (19 males, 26 females; age range 7 months to 50 years). We provide guidance about the potential pitfalls in the laboratory testing and emphasise the challenges of KANSL1 variant calling and DNA copy number analysis in the complex 17q21.31 region. Moreover, we present detailed phenotypic information, including neuropsychological features, that contribute to the broad phenotypic spectrum of the syndrome. Comparison of the phenotype of both the microdeletion and SNV patients does not show differences of clinical importance, stressing that haploinsufficiency of KANSL1 is sufficient to cause the full KdVS phenotype.
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http://dx.doi.org/10.1038/ejhg.2015.178DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4930086PMC
May 2016

A study of the clinical and radiological features in a cohort of 93 patients with a COL2A1 mutation causing spondyloepiphyseal dysplasia congenita or a related phenotype.

Am J Med Genet A 2015 Mar 21;167A(3):461-75. Epub 2015 Jan 21.

Department of Medical Genetics, University Medical Centre Utrecht, Utrecht, The Netherlands.

Type 2 collagen disorders encompass a diverse group of skeletal dysplasias that are commonly associated with orthopedic, ocular, and hearing problems. However, the frequency of many clinical features has never been determined. We retrospectively investigated the clinical, radiological, and genotypic data in a group of 93 patients with molecularly confirmed SEDC or a related disorder. The majority of the patients (80/93) had short stature, with radiological features of SEDC (n = 64), others having SEMD (n = 5), Kniest dysplasia (n = 7), spondyloperipheral dysplasia (n = 2), or Torrance-like dysplasia (n = 2). The remaining 13 patients had normal stature with mild SED, Stickler-like syndrome or multiple epiphyseal dysplasia. Over 50% of the patients had undergone orthopedic surgery, usually for scoliosis, femoral osteotomy or hip replacement. Odontoid hypoplasia was present in 56% (95% CI 38-74) and a correlation between odontoid hypoplasia and short stature was observed. Atlanto-axial instability, was observed in 5 of the 18 patients (28%, 95% CI 10-54) in whom flexion-extension films of the cervical spine were available; however, it was rarely accompanied by myelopathy. Myopia was found in 45% (95% CI 35-56), and retinal detachment had occurred in 12% (95% CI 6-21; median age 14 years; youngest age 3.5 years). Thirty-two patients complained of hearing loss (37%, 95% CI 27-48) of whom 17 required hearing aids. The ophthalmological features and possibly also hearing loss are often relatively frequent and severe in patients with splicing mutations. Based on clinical findings, age at onset and genotype-phenotype correlations in this cohort, we propose guidelines for the management and follow-up in this group of disorders.
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http://dx.doi.org/10.1002/ajmg.a.36922DOI Listing
March 2015

Further delineation of the KAT6B molecular and phenotypic spectrum.

Eur J Hum Genet 2015 Sep 26;23(9):1165-70. Epub 2014 Nov 26.

Manchester Centre For Genomic Medicine, University of Manchester, St Mary's Hospital, Manchester Academic Health Science Centre, Manchester, UK.

KAT6B sequence variants have been identified previously in both patients with the Say-Barber-Biesecker type of blepharophimosis mental retardation syndromes (SBBS) and in the more severe genitopatellar syndrome (GPS). We report on the findings in a previously unreported group of 57 individuals with suggestive features of SBBS or GPS. Likely causative variants have been identified in 34/57 patients and were commonly located in the terminal exons of KAT6B. Of those where parental samples could be tested, all occurred de novo. Thirty out of thirty-four had truncating variants, one had a missense variant and the remaining three had the same synonymous change predicted to affect splicing. Variants in GPS tended to occur more proximally to those in SBBS patients, and genotype/phenotype analysis demonstrated significant clinical overlap between SBBS and GPS. The de novo synonymous change seen in three patients with features of SBBS occurred more proximally in exon 16. Statistical analysis of clinical features demonstrated that KAT6B variant-positive patients were more likely to display hypotonia, feeding difficulties, long thumbs/great toes and dental, thyroid and patella abnormalities than KAT6B variant-negative patients. The few reported patients with KAT6B haploinsufficiency had a much milder phenotype, though with some features overlapping those of SBBS. We report the findings in a previously unreported patient with a deletion of the KAT6B gene to further delineate the haploinsufficiency phenotype. The molecular mechanisms giving rise to the SBBS and GPS phenotypes are discussed.
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http://dx.doi.org/10.1038/ejhg.2014.248DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4351891PMC
September 2015

Central 22q11.2 deletions.

Am J Med Genet A 2014 Nov 14;164A(11):2707-23. Epub 2014 Aug 14.

University of Groningen, University Medical Centre Groningen, Department of Genetics, Groningen, The Netherlands.

22q11.2 deletion syndrome is one of the most common microdeletion syndromes. Most patients have a deletion resulting from a recombination of low copy repeat blocks LCR22-A and LCR22-D. Loss of the TBX1 gene is considered the most important cause of the phenotype. A limited number of patients with smaller, overlapping deletions distal to the TBX1 locus have been described in the literature. In these patients, the CRKL gene is deleted. Haploinsufficiency of this gene has also been implicated in the pathogenesis of 22q11.2 deletion syndrome. To distinguish these deletions (comprising the LCR22-B to LCR22-D region) from the more distal 22q11.2 deletions (located beyond LCR22-D), we propose the term "central 22q11.2 deletions". In the present study we report on 27 new patients with such a deletion. Together with information on previously published cases, we review the clinical findings of 52 patients. The prevalence of congenital heart anomalies and the frequency of de novo deletions in patients with a central deletion are substantially lower than in patients with a common or distal 22q11.2 deletion. Renal and urinary tract malformations, developmental delays, cognitive impairments and behavioral problems seem to be equally frequent as in patients with a common deletion. None of the patients had a cleft palate. Patients with a deletion that also encompassed the MAPK1 gene, located just distal to LCR22-D, have a different and more severe phenotype, characterized by a higher prevalence of congenital heart anomalies, growth restriction and microcephaly. Our results further elucidate genotype-phenotype correlations in 22q11.2 deletion syndrome spectrum.
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http://dx.doi.org/10.1002/ajmg.a.36711DOI Listing
November 2014

Mutations in NEK8 link multiple organ dysplasia with altered Hippo signalling and increased c-MYC expression.

Hum Mol Genet 2013 Jun 14;22(11):2177-85. Epub 2013 Feb 14.

Center for Human Genetics, Bioscientia, Ingelheim 55218, Germany.

Mutations affecting the integrity and function of cilia have been identified in various genes over the last decade accounting for a group of diseases called ciliopathies. Ciliopathies display a broad spectrum of phenotypes ranging from mild manifestations to lethal combinations of multiple severe symptoms and most of them share cystic kidneys as a common feature. Our starting point was a consanguineous pedigree with three affected fetuses showing an early embryonic phenotype with enlarged cystic kidneys, liver and pancreas and developmental heart disease. By genome-wide linkage analysis, we mapped the disease locus to chromosome 17q11 and identified a homozygous nonsense mutation in NEK8/NPHP9 that encodes a kinase involved in ciliary dynamics and cell cycle progression. Missense mutations in NEK8/NPHP9 have been identified in juvenile cystic kidney jck mice and in patients suffering from nephronophthisis (NPH), an autosomal-recessive cystic kidney disease. This work confirmed a complete loss of NEK8 expression in the affected fetuses due to nonsense-mediated decay. In cultured fibroblasts derived from these fetuses, the expression of prominent polycystic kidney disease genes (PKD1 and PKD2) was decreased, whereas the oncogene c-MYC was upregulated, providing potential explanations for the observed renal phenotype. We furthermore linked NEK8 with NPHP3, another NPH protein known to cause a very similar phenotype in case of null mutations. Both proteins interact and activate the Hippo effector TAZ. Taken together, our study demonstrates that NEK8 is essential for organ development and that the complete loss of NEK8 perturbs multiple signalling pathways resulting in a severe early embryonic phenotype.
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http://dx.doi.org/10.1093/hmg/ddt070DOI Listing
June 2013

Functional and genetic characterization of two extremely rare cases of Williams-Beuren syndrome associated with chronic granulomatous disease.

Eur J Hum Genet 2013 Oct 23;21(10):1079-84. Epub 2013 Jan 23.

1] Chronic Granulomatous Disease Diagnosis and Research Centre, Therex-TIMC/Imag, UMR CNRS 5525, UJF-Grenoble 1, Grenoble, France [2] Pôle Biologie, CHU de Grenoble, Grenoble, France.

Williams-Beuren syndrome (WBS) is a neurodevelopmental disorder with multi-systemic manifestations, caused by a heterozygous segmental deletion of 1.55-1.83 Mb at chromosomal band 7q11.23. The deletion can include the NCF1 gene that encodes the p47(phox) protein, a component of the leukocyte NADPH oxidase enzyme, which is essential for the defense against microbial pathogens. It has been postulated that WBS patients with two functional NCF1 genes are more susceptible to occurrence of hypertension than WBS patients with only one functional NCF1 gene. We now describe two extremely rare WBS patients without any functional NCF1 gene, because of a mutation in NCF1 on the allele not carrying the NCF1-removing WBS deletion. These two patients suffer from chronic granulomatous disease with increased microbial infections in addition to WBS. Interestingly, one of these patients did suffer from hypertension, indicating that other factors than NADPH oxidase in vascular tissue may be involved in causing hypertension.
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http://dx.doi.org/10.1038/ejhg.2012.310DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3778347PMC
October 2013

Dysmorphic features in 2-year-old IVF/ICSI offspring.

Early Hum Dev 2012 Oct 12;88(10):823-9. Epub 2012 Jul 12.

Dept. Pediatrics, Div. Developmental Neurology, University Medical Center Groningen, The Netherlands.

Background: An increased risk of major congenital abnormalities after IVF and ICSI has been described, but underlying mechanisms are unclear. This study evaluates the effects of ovarian hyperstimulation, the in vitro procedure and time to pregnancy (TTP) - as proxy for the severity of subfertility - on the prevalence of dysmorphic features.

Design/methods: Participants were singletons born following controlled ovarian hyperstimulation-IVF/ICSI (COH-IVF/ICSI; n=66), or modified natural cycle-IVF/ICSI (MNC-IVF/ICSI; n=56), or to subfertile couples who conceived naturally (Sub-NC; n=86). Dysmorphic features were assessed according to the method of Merks et al., and are classified into 'minor variants' (minor anomalies or common variants) and 'abnormalities' (clinically relevant or irrelevant abnormalities). We focussed on minor anomalies as they indicate altered embryonic development and because they have the advantage of a higher prevalence.

Results: The prevalences of any of the outcome measures were similar in the three groups. One or more minor anomalies, our primary outcome measure, occurred in 50% of COH-IVF/ICSI, 54% of MNC-IVF/ICSI and 53% of Sub-NC children. TTP in years was significantly associated with abnormalities (adjustedOR=1.20; 95%CI=1.02-1.40), especially with clinically relevant abnormalities (adjustedOR=1.22; 95%CI=1.01-1.48).

Conclusions: The study indicates that ovarian hyperstimulation and the in vitro procedure are not associated with an increase in dysmorphic features. The positive association between TTP and clinically relevant abnormalities suggests a role of the underlying subfertility and its determinants in the genesis of dysmorphic features.
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http://dx.doi.org/10.1016/j.earlhumdev.2012.06.002DOI Listing
October 2012

Practical guidelines for interpreting copy number gains detected by high-resolution array in routine diagnostics.

Eur J Hum Genet 2012 Feb 21;20(2):161-5. Epub 2011 Sep 21.

Department of Genetics, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands.

The correct interpretation of copy number gains in patients with developmental delay and multiple congenital anomalies is hampered by the large number of copy number variations (CNVs) encountered in healthy individuals. The variable phenotype associated with copy number gains makes interpretation even more difficult. Literature shows that inheritence, size and presence in healthy individuals are commonly used to decide whether a certain copy number gain is pathogenic, but no general consensus has been established. We aimed to develop guidelines for interpreting gains detected by array analysis using array CGH data of 300 patients analysed with the 105K Agilent oligo array in a diagnostic setting. We evaluated the guidelines in a second, independent, cohort of 300 patients. In the first 300 patients 797 gains of four or more adjacent oligonucleotides were observed. Of these, 45.4% were de novo and 54.6% were familial. In total, 94.8% of all de novo gains and 87.1% of all familial gains were concluded to be benign CNVs. Clinically relevant gains ranged from 288 to 7912 kb in size, and were significantly larger than benign gains and gains of unknown clinical relevance (P < 0.001). Our study showed that a threshold of 200 kb is acceptable in a clinical setting, whereas heritability does not exclude a pathogenic nature of a gain. Evaluation of the guidelines in the second cohort of 300 patients revealed that the interpretation guidelines were clear, easy to follow and efficient.
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http://dx.doi.org/10.1038/ejhg.2011.174DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3260923PMC
February 2012

Paediatric intestinal cancer and polyposis due to bi-allelic PMS2 mutations: case series, review and follow-up guidelines.

Eur J Cancer 2011 May 4;47(7):965-82. Epub 2011 Mar 4.

Department of Genetics, University Medical Center Groningen, University of Groningen, P.O. Box 30.001, 9700 RB Groningen, The Netherlands.

Background: Bi-allelic germline mutations of one of the DNA mismatch repair genes, so far predominantly found in PMS2, cause constitutional MMR-deficiency syndrome. This rare disorder is characterised by paediatric intestinal cancer and other malignancies. We report the clinical, immunohistochemical and genetic characterisation of four families with bi-allelic germline PMS2 mutations. We present an overview of the published gastrointestinal manifestations of CMMR-D syndrome and propose recommendations for gastro-intestinal screening.

Methods And Results: The first proband developed a cerebral angiosarcoma at age 2 and two colorectal adenomas at age 7. Genetic testing identified a complete PMS2 gene deletion and a frameshift c.736_741delinsTGTGTGTGAAG (p.Pro246CysfsX3) mutation. In the second family, both the proband and her brother had multiple intestinal adenomas, initially wrongly diagnosed as familial adenomatous polyposis. A splice site c.2174+1G>A, and a missense c.137G>T (p.Ser46Ile) mutation in PMS2 were identified. The third patient was diagnosed with multiple colorectal adenomas at age 11; he developed a high-grade dysplastic colorectal adenocarcinoma at age 21. Two intragenic PMS2 deletions were found. The fourth proband developed a cerebral anaplastic ganglioma at age 9 and a high-grade colerectal dysplastic adenoma at age 10 and carries a homozygous c.2174+1G>A mutation. Tumours of all patients showed microsatellite instability and/or loss of PMS2 expression.

Conclusions: Our findings show the association between bi-allelic germline PMS2 mutations and severe childhood-onset gastrointestinal manifestations, and support the notion that patients with early-onset gastrointestinal adenomas and cancer should be investigated for CMMR-D syndrome. We recommend yearly follow-up with colonoscopy from age 6 and simultaneous video-capsule small bowel enteroscopy from age 8.
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http://dx.doi.org/10.1016/j.ejca.2011.01.013DOI Listing
May 2011

Expanding the spectrum of FOXC1 and PITX2 mutations and copy number changes in patients with anterior segment malformations.

Invest Ophthalmol Vis Sci 2011 Jan 21;52(1):324-33. Epub 2011 Jan 21.

Center for Medical Genetics, Department of Ophthalmology, Ghen University Hospital, Ghent, Belgium.

Purpose: Anterior segment dysgenesis (ASD) comprises a heterogeneous group of developmental abnormalities that affect several structures of the anterior segment of the eye. The main purpose of this study was to assess the proportion of FOXC1 and PITX2 mutations and copy number changes in 80 probands with ASD.

Methods: The patients were examined for FOXC1 and PITX2 copy number changes and mutations using MLPA (multiplex ligation-dependent probe amplification) and direct sequencing. Subsequently, the identified copy number changes were fine-mapped using high-resolution microarrays. In the remaining mutation-negative patients, sequencing of the FOXC1 andPITX2 3' untranslated regions (UTRs) and three other candidate genes (P32, PDP2, and FOXC2) was performed.

Results: Thirteen FOXC1 and eight PITX2 mutations were identified, accounting for 26% (21/80) of the cases. In addition, six FOXC1 and five PITX2 deletions were found, explaining 14% (11/80) of the cases. The smallest FOXC1 and PITX2 deletions were 5.4 and 1.6 kb in size, respectively. Six patients carrying FOXC1 deletions presented with variable extraocular phenotypic features such as hearing defects (in 4/6) and mental retardation (in 2/6). No further genetic defects were found in the remaining mutation-negative patients.

Conclusions: FOXC1 and PITX2 genetic defects explain 40% of our large ASD cohort. The current spectrum of intragenic FOXC1 and PITX2 mutations was extended considerably, the identified copy number changes were fine mapped, the smallest FOXC1 and PITX2 deletions reported so far were identified, and the need for dedicated copy number screening of the FOXC1 and PITX2 genomic landscape was emphasized. This study is unique in that sequence and copy number changes were screened simultaneously in both genes.
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http://dx.doi.org/10.1167/iovs.10-5309DOI Listing
January 2011

Functional analysis of novel TBX5 T-box mutations associated with Holt-Oram syndrome.

Cardiovasc Res 2010 Oct 2;88(1):130-9. Epub 2010 Jun 2.

Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.

Aims: Holt-Oram syndrome (HOS) is a heart/hand syndrome clinically characterized by upper limb and cardiac malformations. Mutations in T-box transcription factor 5 (TBX5) underlie this syndrome, the majority of which lead to premature stops. In this study, we present our functional analyses of five (novel) missense TBX5 mutations identified in HOS patients, most of whom presented with severe cardiac malformations.

Methods And Results: Functional characterization of mutant proteins shows a dramatic loss of DNA-binding capacity, as well as diminished binding to known cardiac interaction partners NKX2-5 and GATA4. The disturbance of these interactions leads to a loss of function, as measured by the reduced activation of Nppa and FGF10 in rat heart derived cells, although with variable severity. Two out of the five mutations are peculiar: one, p.H220del, is associated with additional extra-cardiac defects, perhaps by interfering with other T-box dependant pathways, and another, p.I106V, leads to limb defects only, which is supported by its normal interaction with cardiac-specific interaction partners.

Conclusion: Overall, our data are consistent with the hypothesis that these novel missense mutations in TBX5 lead to functional haploinsufficiency and result in a reduced transcriptional activation of target genes, which is likely central to the pathogenesis of HOS.
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http://dx.doi.org/10.1093/cvr/cvq178DOI Listing
October 2010

Severe cardiac phenotype with right ventricular predominance in a large cohort of patients with a single missense mutation in the DES gene.

Heart Rhythm 2009 Nov 28;6(11):1574-83. Epub 2009 Jul 28.

Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.

Background: Desmin-related myopathy is a clinically heterogenous group of disorders encompassing myopathies, cardiomyopathies, conduction disease, and combinations of these disorders. Mutations in the gene encoding desmin (DES), a major intermediate filament protein, can underlie this phenotype.

Objective: The purpose of this study was to investigate the clinical and pathologic characteristics of 27 patients from five families with an identical mutation in the head domain region (p.S13F) of desmin.

Methods/results: All 27 carriers or obligate carriers of a p.S13F DES founder mutation demonstrated a fully penetrant yet variable phenotype. All patients demonstrated cardiac involvement characterized by high-grade AV block at young ages and important right ventricular (RV) involvement. RV predominance was demonstrated by the presence of right bundle branch block in 10 patients (sometimes as a first manifestation) and by RV heart failure in 6 patients, including 2 patients who fulfilled the diagnostic criteria for arrhythmogenic RV cardiomyopathy. Because of this clinical overlap with desmosome cardiomyopathies, we also studied the organization of the intercalated disks, particularly the distribution of desmosomal proteins. Normal amounts of the major desmosomal proteins were found, but the intercalated disks were more convoluted and elongated and had a zigzag appearance.

Conclusion: In this largest series to date of individuals with a single head domain DES mutation, patients show a variable yet predominantly cardiologic phenotype characterized by conduction disease at an early age and RV involvement including right bundle branch block and/or RV tachycardias and arrhythmogenic RV cardiomyopathy phenocopies. A localized effect of desmin on the structure of the cardiac intercalated disks might contribute to disease pathogenesis.
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http://dx.doi.org/10.1016/j.hrthm.2009.07.041DOI Listing
November 2009

Two related Dutch families with a clinically variable presentation of cardioskeletal myopathy caused by a novel S13F mutation in the desmin gene.

Eur J Med Genet 2007 Sep-Oct;50(5):355-66. Epub 2007 Jul 15.

Department of Genetics, University Medical Center Groningen, University of Groningen, Post Box 30001, 9700 RB Groningen, The Netherlands.

Desmin-related myopathy is characterised by skeletal muscle weakness often combined with cardiac involvement. Mutations in the desmin gene have been described as a cause of desmin-related myopathy (OMIM 601419). We report here on two distantly related Dutch families with autosomal dominant inheritance of desmin-related myopathy affecting 15 family members. A highly heterogeneous clinical picture is apparent, varying from isolated dilated cardiomyopathy to a more generalised skeletal myopathy and mild respiratory problems. Morphological analysis of muscle biopsies revealed intracytoplasmic desmin aggregates (desmin and p62 staining). In both families we identified an identical novel pathogenic heterozygous missense mutation, S13F, in the 'head' domain of the desmin gene which cosegregates with the disease phenotype. This is the 5th reported missense mutation located at the 'head' domain of the desmin gene and the first reported Dutch family with desmin-related myopathy. This article illustrates the importance of analysing the desmin gene in patients with (familial) cardiac conduction disease, dilated cardiomyopathy and/or a progressive skeletal myopathy resembling limb-girdle muscular dystrophy.
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http://dx.doi.org/10.1016/j.ejmg.2007.06.003DOI Listing
November 2007

Early recognition of basal cell naevus syndrome.

Eur J Pediatr 2005 Mar 10;164(3):126-30. Epub 2004 Dec 10.

Department of Clinical Genetics, University Hospital Groningen, Groningen, The Netherlands.

Unlabelled: The basal cell naevus syndrome is an autosomal dominant syndrome characterised by major manifestations such as basal cell carcinomas, jaw cysts, palmar or plantar pits, and intracranial calcifications. Early recognition is important in order to reduce morbidity due to cutaneous and cerebral malignancy and oromaxillofacial deformation and destruction, although diagnosis in infancy is rare. We describe three unrelated children with basal cell naevus syndrome who appeared to be the first patient in each family.

Conclusion: Our observations lead us to recommend looking for other manifestations of this disease in patients who present with cardiac fibroma, cleft lip/palate, polydactyly or macrocephaly. Bifid, fused or splayed ribs should be considered a major criterion of great help in establishing a diagnosis, particularly in young children.
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http://dx.doi.org/10.1007/s00431-004-1597-4DOI Listing
March 2005

Genotype-phenotype correlation in patients suspected of having Sotos syndrome.

Horm Res 2004 24;62(4):197-207. Epub 2004 Sep 24.

Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands.

Background: Deletions and mutations in the NSD1 gene are the major cause of Sotos syndrome. We wanted to evaluate the genotype-phenotype correlation in patients suspected of having Sotos syndrome and determine the best discriminating parameters for the presence of a NSD1 gene alteration.

Methods: Mutation and fluorescence in situ hybridization analysis was performed on blood samples of 59 patients who were clinically scored into 3 groups. Clinical data were compared between patients with and without NSD1 alterations. With logistic regression analysis the best combination of predictive variables was obtained.

Results: In the groups of typical, dubious and atypical Sotos syndrome, 81, 36 and 0% of the patients, respectively, showed NSD1 gene alterations. Four deletions were detected. In 23 patients (2 families) 19 mutations were detected (1 splicing defect, 3 non-sense, 7 frameshift and 8 missense mutations). The best predictive parameters for a NSD1 gene alteration were frontal bossing, down-slanted palpebral fissures, pointed chin and overgrowth. Higher incidences of feeding problems and cardiac anomalies were found. The parameters, delayed development and advanced bone age, did not differ between the 2 subgroups.

Conclusions: In our patients suspected of having Sotos syndrome, facial features and overgrowth were highly predictive of a NSD1 gene aberration, whereas developmental delay and advanced bone age were not.
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http://dx.doi.org/10.1159/000081063DOI Listing
February 2005