Publications by authors named "Diana Mitter"

28 Publications

  • Page 1 of 1

Germline AGO2 mutations impair RNA interference and human neurological development.

Nat Commun 2020 11 16;11(1):5797. Epub 2020 Nov 16.

Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada.

ARGONAUTE-2 and associated miRNAs form the RNA-induced silencing complex (RISC), which targets mRNAs for translational silencing and degradation as part of the RNA interference pathway. Despite the essential nature of this process for cellular function, there is little information on the role of RISC components in human development and organ function. We identify 13 heterozygous mutations in AGO2 in 21 patients affected by disturbances in neurological development. Each of the identified single amino acid mutations result in impaired shRNA-mediated silencing. We observe either impaired RISC formation or increased binding of AGO2 to mRNA targets as mutation specific functional consequences. The latter is supported by decreased phosphorylation of a C-terminal serine cluster involved in mRNA target release, increased formation of dendritic P-bodies in neurons and global transcriptome alterations in patient-derived primary fibroblasts. Our data emphasize the importance of gene expression regulation through the dynamic AGO2-RNA association for human neuronal development.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-020-19572-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7670403PMC
November 2020

Defining and expanding the phenotype of -associated developmental epileptic encephalopathy.

Neurol Genet 2019 Dec 10;5(6):e373. Epub 2019 Dec 10.

Department of Epilepsy Genetics and Precision Medicine (K.J.M., E.G., G.R., R.S.M.), The Danish Epilepsy Centre Filadelfia, Dianalund, Denmark; Institute for Regional Health Services (K.J.M., E.G., R.S.M.), University of Southern Denmark, Odense; Institute of Human Genetics (D.M., R. Jamra, A.F., J.R.L.), University of Leipzig Medical Center, Germany; Institute of Structural Biology (R. Janowski, D.N.), Helmholtz Zentrum München - German Research Center for Environmental Health, Neuherberg, Germany; Department of Paediatric Radiology (C.R.), University of Leipzig Medical Center, Germany; Department of Epilepsy, Sleep and Pediatric Neurophysiology (J.T.), Lyon University Hospital, France; Neuropediatric Unit (A.-L.P., D.M.V., G.L.), Lyon University Hospital, France; Department of Medical Genetics (N.C., G.L.), Lyon University Hospital, France; GenDev Team (N.C.), CNRS UMR 5292, INSERM U1028, CNRL and University of Lyon, France; Department of Genetics (E.B.), University Medical Center Utrecht, The Netherlands; Department of Child Neurology (K.G.), Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands; Department of Paediatrics (A.P.B.), Copenhagen University Hospital Rigshospitalet, Denmark; Baylor College of Medicine (S.M., K.N.), Children's Hospital of San Antonio; Undiagnosed Diseases Program (G.B., C.P.), Genetic Services of Western Australia, Department of Health, Government of Western Australia, Perth; Western Australian Register of Developmental Anomalies (G.B., D.G.), Australia; Telethon Kids Institute and the School of Paediatrics and Child Health (G.B.), University of Western Australia, Perth; Linear Clinical Research (L.D.), WA, Australia; Center of Human Genetics (S.S), Jena University Hospital, Germany; Department of Neuropediatrics (A.D.), Jena University Hospital, Germany; Division of Neurology (K.L.H.), Children's Hospital of Philadelphia, PA; Division of Neuropediatrics (A.M.), University of Leipzig Medical Center, Germany; Amplexa Genetics (H.H.), Odense, Denmark; Clinic for Children (H.H.), Værløse, Denmark; Center for Integrative Brain Research (G.M.), Seattle Children's Research Institute, WA; Department of Pediatrics (G.M.), University of Washington, Seattle; Medical Genetics Unit (F.B.), Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy; Istituto Dermopatico dell'Immacolata (F.B.), IDI-IRCCS, Rome, Italy; Institute of Human Genetics (T.B., M.H.), University Medical Center Hamburg-Eppendorf, Germany; Childrens Hospital (J.D.), University Medical Center Hamburg-Eppendorf, Germany; University of Copenhagen (G.R.), Denmark; Institute for Human Genetics (P.M.), University Hospital Magdeburg, Germany; Children's Hospital A. Meyer (R.G., A.V.), University of Florence, Italy; and Institute of Pharmaceutical Biotechnology (D.N.), Ulm University, Germany.

Objective: The study is aimed at widening the clinical and genetic spectrum and at assessing genotype-phenotype associations in encephalopathy.

Methods: Through diagnostic gene panel screening in an epilepsy cohort, and recruiting through GeneMatcher and our international network, we collected 10 patients with biallelic variants. In addition, we collected data on 12 patients described in the literature to further delineate the associated phenotype in a total cohort of 22 patients. Computer modeling was used to assess changes on protein folding.

Results: Biallelic pathogenic variants in cause a triad of progressive microcephaly, moderate to severe developmental delay, and early-onset epilepsy. Microcephaly was present at birth in 65%, and in all patients at follow-up. Moderate (14%) or severe (73%) developmental delay was characteristic, with no achievement of sitting (85%), walking (86%), or talking (90%). Additional features included irritability (91%), hypertonia/spasticity (75%), hypotonia (83%), stereotypic movements (75%), and short stature (56%). Seventy-nine percent had pharmacoresistant epilepsy with mainly neonatal onset. Characteristic cranial MRI findings include early-onset progressive atrophy of cerebral cortex (89%) and cerebellum (61%), enlargement of ventricles (95%), and age-dependent delayed myelination (88%). A small subset of patients displayed a less severe phenotype.

Conclusions: These data revealed first genotype-phenotype associations and may serve for improved interpretation of new variants and well-founded genetic counseling.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1212/NXG.0000000000000373DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6927360PMC
December 2019

Genetical, clinical, and functional analysis of a large international cohort of patients with autosomal recessive congenital ichthyosis due to mutations in NIPAL4.

Hum Mutat 2019 12 6;40(12):2318-2333. Epub 2019 Sep 6.

Institute of Human Genetics, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Autosomal recessive congenital ichthyosis (ARCI) belongs to a heterogeneous group of disorders of keratinization. To date, 10 genes have been identified to be causative for ARCI. NIPAL4 (Nipa-Like Domain-Containing 4) is the second most commonly mutated gene in ARCI. In this study, we present a large cohort of 101 families affected with ARCI carrying mutations in NIPAL4. We identified 16 novel mutations and increase the total number of pathogenic mutations in NIPAL4 to 34. Ultrastructural analysis of biopsies from six patients showed morphological abnormalities consistent with an ARCI EM type III. One patient with a homozygous splice site mutation, which leads to a loss of NIPAL4 mRNA, showed additional ultrastructural aberrations together with a more severe clinical phenotype. Our study gives insights into the frequency of mutations, a potential hot spot for mutations, and genotype-phenotype correlations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/humu.23883DOI Listing
December 2019

PEDIA: prioritization of exome data by image analysis.

Genet Med 2019 12 5;21(12):2807-2814. Epub 2019 Jun 5.

National Research and Applied Medicine Centre 'Mother and Child'', Minsk, Belarus.

Purpose: Phenotype information is crucial for the interpretation of genomic variants. So far it has only been accessible for bioinformatics workflows after encoding into clinical terms by expert dysmorphologists.

Methods: Here, we introduce an approach driven by artificial intelligence that uses portrait photographs for the interpretation of clinical exome data. We measured the value added by computer-assisted image analysis to the diagnostic yield on a cohort consisting of 679 individuals with 105 different monogenic disorders. For each case in the cohort we compiled frontal photos, clinical features, and the disease-causing variants, and simulated multiple exomes of different ethnic backgrounds.

Results: The additional use of similarity scores from computer-assisted analysis of frontal photos improved the top 1 accuracy rate by more than 20-89% and the top 10 accuracy rate by more than 5-99% for the disease-causing gene.

Conclusion: Image analysis by deep-learning algorithms can be used to quantify the phenotypic similarity (PP4 criterion of the American College of Medical Genetics and Genomics guidelines) and to advance the performance of bioinformatics pipelines for exome analysis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41436-019-0566-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6892739PMC
December 2019

Structural brain anomalies in patients with FOXG1 syndrome and in Foxg1+/- mice.

Ann Clin Transl Neurol 2019 Apr 3;6(4):655-668. Epub 2019 Mar 3.

Institut für Medizinische Genetik und angewandte Genomik Universitätsklinikum Tübingen Tübingen Germany.

Objective: FOXG1 syndrome is a rare neurodevelopmental disorder associated with heterozygous variants or chromosomal microaberrations in 14q12. The study aimed at assessing the scope of structural cerebral anomalies revealed by neuroimaging to delineate the genotype and neuroimaging phenotype associations.

Methods: We compiled 34 patients with a heterozygous (likely) pathogenic variant. Qualitative assessment of cerebral anomalies was performed by standardized re-analysis of all 34 MRI data sets. Statistical analysis of genetic, clinical and neuroimaging data were performed. We quantified clinical and neuroimaging phenotypes using severity scores. Telencephalic phenotypes of adult +/- mice were examined using immunohistological stainings followed by quantitative evaluation of structural anomalies.

Results: Characteristic neuroimaging features included corpus callosum anomalies (82%), thickening of the fornix (74%), simplified gyral pattern (56%), enlargement of inner CSF spaces (44%), hypoplasia of basal ganglia (38%), and hypoplasia of frontal lobes (29%). We observed a marked, filiform thinning of the rostrum as recurrent highly typical pattern of corpus callosum anomaly in combination with distinct thickening of the fornix as a characteristic feature. Thickening of the fornices was not reported previously in FOXG1 syndrome. Simplified gyral pattern occurred significantly more frequently in patients with early truncating variants. Higher clinical severity scores were significantly associated with higher neuroimaging severity scores. Modeling of heterozygosity in mouse brain recapitulated the associated abnormal cerebral morphology phenotypes, including the striking enlargement of the fornix.

Interpretation: Combination of specific corpus callosum anomalies with simplified gyral pattern and hyperplasia of the fornices is highly characteristic for FOXG1 syndrome.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/acn3.735DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6469254PMC
April 2019

Next-generation sequencing of 32 genes associated with hereditary aortopathies and related disorders of connective tissue in a cohort of 199 patients.

Genet Med 2019 08 24;21(8):1832-1841. Epub 2019 Jan 24.

Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.

Purpose: Heritable factors play an important etiologic role in connective tissue disorders (CTD) with vascular involvement, and a genetic diagnosis is getting increasingly important for gene-tailored, personalized patient management.

Methods: We analyzed 32 disease-associated genes by using targeted next-generation sequencing and exome sequencing in a clinically relevant cohort of 199 individuals. We classified and refined sequence variants according to their likelihood for pathogenicity.

Results: We identified 1 pathogenic variant (PV; in FBN1 or SMAD3) in 15 patients (7.5%) and ≥1 likely pathogenic variant (LPV; in COL3A1, FBN1, FBN2, LOX, MYH11, SMAD3, TGFBR1, or TGFBR2) in 19 individuals (9.6%), together resulting in 17.1% diagnostic yield. Thirteen PV/LPV were novel. Of PV/LPV-negative patients 47 (23.6%) showed ≥1 variant of uncertain significance (VUS). Twenty-five patients had concomitant variants. In-depth evaluation of reported/calculated variant classes resulted in reclassification of 19.8% of variants.

Conclusion: Variant classification and refinement are essential for shaping mutational spectra of disease genes, thereby improving clinical sensitivity. Obligate stringent multigene analysis is a powerful tool for identifying genetic causes of clinically related CTDs. Nonetheless, the relatively high rate of PV/LPV/VUS-negative patients underscores the existence of yet unknown disease loci and/or oligogenic/polygenic inheritance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41436-019-0435-zDOI Listing
August 2019

Haploinsufficiency of CUX1 Causes Nonsyndromic Global Developmental Delay With Possible Catch-up Development.

Ann Neurol 2018 08 31;84(2):200-207. Epub 2018 Aug 31.

Institute of Human Genetics, University of Leipzig Hospitals and Clinics, Leipzig, Germany.

Objective: Developmental delay (DD) with favorable intellectual outcome and mild intellectual disability (ID) are mostly considered to be of complex genetic and environmental origin, but, in fact, often remain unclear. We aimed at proving our assumption that also mild cases of DD and ID may be of monogenic etiology.

Methods: We clinically evaluated 8 individuals and performed exome sequencing or array copy number analysis and identified variants in CUX1 as the likely cause. In addition, we included a case from the public database, DECIPHER.

Results: All 9 individuals harbored heterozygous null-allele variants in CUX1, encoding the Cut-homeobox 1 transcription factor that is involved in regulation of dendritogenesis and cortical synapse formation in layer II to IV cortical neurons. Six variants arose de novo, while in one family the variant segregated with ID. Of the 9 included individuals, 2 were diagnosed with moderate ID, 3 with mild ID, and 3 showed a normal age-related intelligence at ages 4, 6, and 8 years after a previous history of significant DD.

Interpretation: Our results suggest that null-allele variants, and thus haploinsufficiency of CUX1, cause an isolated phenotype of DD or ID with possible catch-up development. This illustrates that such a developmental course is not necessarily genetic complex, but may also be attributed to a monogenic cause. Ann Neurol 2018;84:200-207.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ana.25278DOI Listing
August 2018

Next-generation sequencing reveals the mutational landscape of clinically diagnosed Usher syndrome: copy number variations, phenocopies, a predominant target for translational read-through, and mutated in Heimler syndrome.

Mol Genet Genomic Med 2017 Sep 6;5(5):531-552. Epub 2017 Jul 6.

Bioscientia Center for Human GeneticsIngelheimGermany.

Background: Combined retinal degeneration and sensorineural hearing impairment is mostly due to autosomal recessive Usher syndrome (USH1: congenital deafness, early retinitis pigmentosa (RP); USH2: progressive hearing impairment, RP).

Methods: Sanger sequencing and NGS of 112 genes (Usher syndrome, nonsyndromic deafness, overlapping conditions), MLPA, and array-CGH were conducted in 138 patients clinically diagnosed with Usher syndrome.

Results: A molecular diagnosis was achieved in 97% of both USH1 and USH2 patients, with biallelic mutations in 97% (USH1) and 90% (USH2), respectively. Quantitative readout reliably detected CNVs (confirmed by MLPA or array-CGH), qualifying targeted NGS as one tool for detecting point mutations and CNVs. CNVs accounted for 10% of identified alleles, often to seemingly monoallelic point mutations. We demonstrate PTC124-induced read-through of the common p.Trp3955* nonsense mutation (13% of detected alleles), a potential therapy target. Usher gene mutations were found in most patients with atypical Usher syndrome, but the diagnosis was adjusted in case of double homozygosity for mutations in and , genes implicated in isolated deafness and RP. Two patients with additional enamel dysplasia had biallelic mutations, for the first time linking this gene to Heimler syndrome.

Conclusion: Targeted NGS not restricted to Usher genes proved beneficial in uncovering conditions mimicking Usher syndrome.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/mgg3.312DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5606877PMC
September 2017

Biallelic COL3A1 mutations result in a clinical spectrum of specific structural brain anomalies and connective tissue abnormalities.

Am J Med Genet A 2017 Sep 25;173(9):2534-2538. Epub 2017 Jul 25.

Institut für Medizinische Genetik und Humangenetik, Charité-Universitätsmedizin Berlin, Berlin, Germany.

Vascular Ehlers-Danlos syndrome (type IV) is an autosomal dominant disorder caused by heterozygous variants of COL3A1. We identified biallelic COL3A1 variants in two unrelated families. In a 3-year-old female with developmental delay the nonsense variant c.1282C>T, p.(Arg428*) was detected in combination the c.2057delC, p.(Pro686Leufs*105) frame shift variant. Both compound heterozygous variants were novel. This patient was born with bilateral clubfoot, joint laxity, and dysmorphic facial features. At the age of 2 years she developed an aneurysmal brain hemorrhage. Cerebral MRI showed a peculiar pattern of profound cerebral abnormalities including bilateral frontoparietal polymicrogyria of the cobblestone variant. In the second family, the two affected siblings were homozygous for the missense variant c.145C
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ajmg.a.38345DOI Listing
September 2017

FOXG1 syndrome: genotype-phenotype association in 83 patients with FOXG1 variants.

Genet Med 2018 01 29;20(1):98-108. Epub 2017 Jun 29.

CeGaT, Tübingen, Germany.

PurposeThe study aimed at widening the clinical and genetic spectrum and assessing genotype-phenotype associations in FOXG1 syndrome due to FOXG1 variants.MethodsWe compiled 30 new and 53 reported patients with a heterozygous pathogenic or likely pathogenic variant in FOXG1. We grouped patients according to type and location of the variant. Statistical analysis of molecular and clinical data was performed using Fisher's exact test and a nonparametric multivariate test.ResultsAmong the 30 new patients, we identified 19 novel FOXG1 variants. Among the total group of 83 patients, there were 54 variants: 20 frameshift (37%), 17 missense (31%), 15 nonsense (28%), and 2 in-frame variants (4%). Frameshift and nonsense variants are distributed over all FOXG1 protein domains; missense variants cluster within the conserved forkhead domain. We found a higher phenotypic variability than previously described. Genotype-phenotype association revealed significant differences in psychomotor development and neurological features between FOXG1 genotype groups. More severe phenotypes were associated with truncating FOXG1 variants in the N-terminal domain and the forkhead domain (except conserved site 1) and milder phenotypes with missense variants in the forkhead conserved site 1.ConclusionsThese data may serve for improved interpretation of new FOXG1 sequence variants and well-founded genetic counseling.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/gim.2017.75DOI Listing
January 2018

Genotype and phenotype in patients with Noonan syndrome and a RIT1 mutation.

Genet Med 2016 12 21;18(12):1226-1234. Epub 2016 Apr 21.

Institute of Human Genetics, University Hospital Magdeburg, Magdeburg, Germany.

Purpose: Noonan syndrome (NS) is an autosomal-dominant disorder characterized by craniofacial dysmorphism, growth retardation, cardiac abnormalities, and learning difficulties. It belongs to the RASopathies, which are caused by germ-line mutations in genes encoding components of the RAS mitogen-activated protein kinase (MAPK) pathway. RIT1 was recently reported as a disease gene for NS, but the number of published cases is still limited.

Methods: We sequenced RIT1 in 310 mutation-negative individuals with a suspected RASopathy and prospectively in individuals who underwent genetic testing for NS. Using a standardized form, we recorded clinical features of all RIT1 mutation-positive patients. Clinical and genotype data from 36 individuals with RIT1 mutation reported previously were reviewed.

Results: Eleven different RIT1 missense mutations, three of which were novel, were identified in 33 subjects from 28 families; codons 57, 82, and 95 represent mutation hotspots. In relation to NS of other genetic etiologies, prenatal abnormalities, cardiovascular disease, and lymphatic abnormalities were common in individuals with RIT1 mutation, whereas short stature, intellectual problems, pectus anomalies, and ectodermal findings were less frequent.

Conclusion: RIT1 is one of the major genes for NS. The RIT1-associated phenotype differs gradually from other NS subtypes, with a high prevalence of cardiovascular manifestations, especially hypertrophic cardiomyopathy, and lymphatic problems.Genet Med 18 12, 1226-1234.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/gim.2016.32DOI Listing
December 2016

Identification of a Novel Point Mutation in the LEMD3 Gene in an Infant With Buschke-Ollendorff Syndrome.

JAMA Dermatol 2016 07;152(7):844-5

Department of Dermatology, Venerology, and Allergology, University of Leipzig, Leipzig, Germany.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1001/jamadermatol.2016.0350DOI Listing
July 2016

Late onset dHMN II caused by c.404C>G mutation in HSPB1 gene.

J Peripher Nerv Syst 2016 Jun;21(2):111-113

Department of Neurology, University of Leipzig, Leipzig, Germany.

Distal hereditary motor neuropathy (dHMN) type II is genetically heterogeneous. We report three siblings of a German family with late onset distal motor neuropathy due to the c.404C>G mutation in heat-shock 27-kDa protein 1 gene (HSPB1/HSP27). A 36-year-old mutation carrier, daughter of one sibling, did not present any clinical or electrophysiological abnormalities. The index patient (oldest brother) developed weakness of the distal lower limbs and nocturnal muscle cramps at the age of 54. After 5 years this patient developed an l-DOPA-responsive hypokinetic rigid syndrome, establishing a diagnosis of Parkinson's disease. Although none of the three other mutation carriers displayed Parkinsonian signs, a pathogenic relationship with Parkinson's disease remains a possibility, based on the known molecular pathology of HSPB1. The rare pathogenic HSPB1 c.404C>G mutation may predispose for late-onset of dHMN type II.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/jns.12165DOI Listing
June 2016

A 33-year-old male patient with paternal derived duplication of 14q11.2-14q22.1~22.3: clinical course, phenotypic and genotypic findings.

J Pediatr Endocrinol Metab 2016 May;29(5):611-6

We report on a 33-year-old patient with mosaic interstitial duplication on chromosome 14q11.2-14q22.1~22.3 with severe physical and mental retardation and multiple dysmorphisms. This patient was admitted to our pediatric hospital due to severe dehydration and malnutrition as a result of food refusal. It is an actual phenomenon that patients with severe inborn clinical problems nowadays survive due to progress and care of modern medicine. Nevertheless, transition from pediatric care to adult medicine seems to remain a challenging problem. We demonstrate the clinical course as well as clinical and genetic findings of this adult patient. Comparisons are made to previously reported cases with mosaic trisomy 14 involving a proximal interstitial duplication on the long arm of chromosome 14.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1515/jpem-2015-0375DOI Listing
May 2016

Novel peroxisome proliferator-activated receptor gamma mutation in a family with familial partial lipodystrophy type 3.

Clin Endocrinol (Oxf) 2016 Jan 31;84(1):141-8. Epub 2015 Jul 31.

Department of Human Genetics, University of Halle, Halle, Germany.

Objective: Familial partial lipodystrophy type 3 (FPLD3) is an autosomal dominant disorder with loss of subcutaneous adipose tissue at the extremities and metabolic complications such as insulin resistance, hypertriglyceridaemia and hypertension. The aim of this study was to characterize the molecular basis of a family of 5 affected members with FPLD3.

Methods: A 61-year-old female index patient and her relatives were assessed by detailed clinical and biochemical examinations. Sequence analysis of the LMNA and PPARG gene was performed. Structure analysis of the identified mutation was carried out using published X-ray crystal structures.

Results: A novel heterozygous PPARG mutation c.1040A>C was identified in all 5 patients of the family but not in unaffected controls. The resulting amino acid substitution p.Lys347Thr is located at the ligand-binding domain (LBD) of the protein and is predicted to disrupt critical molecular interactions to the helix 12 of the LBD.

Conclusions: A novel PPARG mutation leading to FPLD3 is described. The results emphasize the importance of the clinical diagnosis and of further molecular genetic analyses in patients with clinical signs of FPLD but unremarkable LMNA findings.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/cen.12837DOI Listing
January 2016

Duplication Xp11.22-p14 in females: does X-inactivation help in assessing their significance?

Am J Med Genet A 2015 Mar;167A(3):553-62

Institute of Human Genetics, Heidelberg University, Heidelberg, Germany.

In females, large duplications in Xp often lead to preferential inactivation of the aberrant X chromosome and a normal phenotype. Recently, a recurrent ∼4.5 Mb microduplication of Xp11.22-p11.23 was found in females with developmental delay/intellectual disability and other neurodevelopmental disorders (speech development disorder, epilepsy or EEG anomalies, autism spectrum disorder, or behavioral disorder). Unexpectedly, most of them showed preferential inactivation of the normal X chromosome. We describe five female patients carrying de novo Xp duplications encompassing p11.23. Patient 1 carried the recurrent microduplication Xp11.22-p11.23, her phenotype and X-chromosome inactivation (XI) pattern was consistent with previous reports. The other four patients had novel Xp duplications. Two were monozygotic twins with a similar phenotype to Patient 1 and unfavorable XI skewing carrying an overlapping ∼5 Mb duplication of Xp11.23-p11.3. Patient 4 showed a duplication of ∼5.5 Mb comparable to the twins but had a more severe phenotype and unskewed XI. Patient 5 had a ∼8.5 Mb duplication Xp11.23-p11.4 and presented with mild ID, epilepsy, behavioral problems, and inconsistent results of XI analysis. A comparison of phenotype, size and location of the duplications and XI patterns in Patients 1-5 and previously reported females with overlapping duplications provides further evidence that microduplications encompassing Xp11.23 are associated with ID and other neurodevelopmental disorders in females. To further assess the implication of XI for female carriers, we recommend systematic analysis of XI pattern in any female with X imbalances that are known or suspected to be pathogenic.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ajmg.a.36897DOI Listing
March 2015

Progeroid laminopathy with restrictive dermopathy-like features caused by an isodisomic LMNA mutation p.R435C.

Aging (Albany NY) 2013 Jun;5(6):445-59

Department of Women and Child Health, Hospital for Children and Adolescents, Centre of Pediatric Research, University Hospital, University of Leipzig, Leipzig, Germany.

The clinical course of a female patient affected by a progeroid syndrome with Restrictive Dermopathy (RD)-like features was followed up. Besides missing hairiness, stagnating weight and growth, RD-like features including progressive skin swelling and solidification, acrocontractures, osteolysis and muscular hypotension were observed until the patient died at the age of 11 months. A homozygousLMNA mutation c.1303C>T (p.R435C) was found by Sanger sequencing. Haplotyping revealed a partial uniparental disomy of chromosome 1 (1q21.3 to 1q23.1) including the LMNA gene. In contrast to reported RD patients with LMNA mutations, LMNA p.R435C is not located at the cleavage site necessary for processing of prelamin A by ZMPSTE24 and leads to a distinct phenotype combining clinical features of Restrictive Dermopathy, Mandibuloacral Dysplasia and Hutchinson-Gilford Progeria. Functionally, LMNA p.R435C is associated with increasing DNA double strand breaks and decreased recruitment of P53 binding protein 1 (53BP1) to DNA-damage sites indicating delayed DNA repair. The follow-up of the complete clinical course in the patient combined with functional studies showed for the first time that a progressive loss of lamin A rather than abnormal accumulation of prelamin A species could be a pathophysiological mechanism in progeroid laminopathies, which leads to DNA repair deficiency accompanied by advancing tissue degeneration.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3824411PMC
http://dx.doi.org/10.18632/aging.100566DOI Listing
June 2013

A mosaic maternal splice donor mutation in the EHMT1 gene leads to aberrant transcripts and to Kleefstra syndrome in the offspring.

Eur J Hum Genet 2013 Aug 12;21(8):887-90. Epub 2012 Dec 12.

Institut für Klinische Genetik, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.

The euchromatic histone-lysine N-methyltransferase 1 (EHMT1) gene was examined in a 3-year-old boy with characteristic clinical features of Kleefstra syndrome. Sequencing of all 27 EHMT1 exons revealed a novel mutation, NM_024757.4:c.2712+1G>A, which affects the splice donor of intron 18. Whereas the index patient is heterozygous for that mutation, his phenotypically normal mother shows tissue-specific mosaicism. Sequencing of EHMT1 RT-PCR products revealed two aberrant transcript variants: in one variant, exon 18 was skipped; in the other, a near-by GT motif was used as splice donor and intronic sequence was inserted between exons 18 and 19. Both transcript variants were found in the patient and his mother. The latter had lower amounts of these transcripts consistent with mosaic status. This is the first description of an EHMT1 point mutation being inherited from a parent with verified mosaicism. The constitutive c.2712+1G>A splice site mutation in EHMT1 is fully pathogenic, and the transcript variants produced do not attenuate the severity of the disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/ejhg.2012.267DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3722677PMC
August 2013

Genotype-phenotype correlations in patients with retinoblastoma and interstitial 13q deletions.

Eur J Hum Genet 2011 Sep 20;19(9):947-58. Epub 2011 Apr 20.

Institut für Humangenetik, Universitätsklinikum Essen, Philipp-Rosenthal-Straße 55, Leipzig, Germany.

Patients with an interstitial 13q deletion that contains the RB1 gene show retinoblastoma and variable clinical features. Relationship between phenotypic expression and loss of specific neighboring genes are unresolved, yet. We obtained clinical, cytogenetic and molecular data in 63 patients with an interstitial 13q deletion involving RB1. Whole-genome array analysis or customized high-resolution array analysis for 13q14.11q14.3 was performed in 38 patients, and cytogenetic analysis was performed in 54 patients. Deletion sizes ranged between 4.2 kb and more than 33.43 Mb; breakpoints were non-recurrent. Sequence analysis of deletion junctions in five patients revealed microhomology and insertion of 2-34 base pairs suggestive of non-homologous end joining. Milder phenotypic expression of retinoblastoma was observed in patients with deletions larger than 1 Mb, which contained the MED4 gene. Clinical features were compared between patients with small (within 13q14), medium (within 13q12.3q21.2) and large (within 13q12q31.2) deletions. Patients with a small deletion can show macrocephaly, tall stature, obesity, motor and/or speech delay. Patients with a medium deletion show characteristic facial features, mild to moderate psychomotor delay, short stature and microcephaly. Patients with a large deletion have characteristic craniofacial dysmorphism, short stature, microcephaly, mild to severe psychomotor delay, hypotonia, constipation and feeding problems. Additional features included deafness, seizures and brain and heart anomalies. We found no correlation between clinical features and parental origin of the deletion. Our data suggest that hemizygous loss of NUFIP1 and PCDH8 may contribute to psychomotor delay, deletion of MTLR1 to microcephaly and loss of EDNRB to feeding difficulties and deafness.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/ejhg.2011.58DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3179359PMC
September 2011

Genotype-phenotype correlation in eight new patients with a deletion encompassing 2q31.1.

Am J Med Genet A 2010 May;152A(5):1213-24

Institut für Humangenetik, Universitätsklinikum Essen, Essen, Germany.

Microdeletions of the 2q31.1 region are rare. We present the clinical and molecular findings of eight previously unreported patients with overlapping deletions in 2q31.1. The patients have a variable clinical phenotype and present with developmental delay (7/8), growth retardation (5/8), seizures (2/8) and a craniofacial dysmorphism consisting of microcephaly (4/8), short palpebral fissures (7/8), broad eyebrows with lateral flare (7/8), low-set ears with thickened helices and lobules (5/8), and micrognathia (6/8). Additional congenital anomalies were noted, including limb abnormalities (8/8), heart defects (3/8), genital anomalies (3/8), and craniosynostosis (1/8). Six of these microdeletions, ranging in size from 1.24 to 8.35 Mb, were identified by array CGH, one larger deletion (19.7 Mb) was detected by conventional karyotyping and further characterized by array CGH analysis. The smallest region of overlap in all eight patients spans at most 88 kb and includes only the WIPF1 gene. This gene codes for the WAS/WASL interacting protein family member 1. The patients described here do not present with clinical signs of the Wiskott-Aldrich syndrome and the deletion of this single gene does not allow explaining the phenotype in our patients. It is likely that the deletion of different but overlapping sets of genes from 2q31 is responsible for the clinical variability in these patients. To further dissect the complex phenotype associated with deletions in 2q31, additional patients with overlapping phenotypes should be examined with array CGH. This should help to link particular phenotypes to specific genes, and add to our understanding of the underlying developmental processes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ajmg.a.33344DOI Listing
May 2010

The human retinoblastoma gene is imprinted.

PLoS Genet 2009 Dec 24;5(12):e1000790. Epub 2009 Dec 24.

Institut für Humangenetik, Universitätsklinikum Essen, Essen, Germany.

Genomic imprinting is an epigenetic process leading to parent-of-origin-specific DNA methylation and gene expression. To date, approximately 60 imprinted human genes are known. Based on genome-wide methylation analysis of a patient with multiple imprinting defects, we have identified a differentially methylated CpG island in intron 2 of the retinoblastoma (RB1) gene on chromosome 13. The CpG island is part of a 5'-truncated, processed pseudogene derived from the KIAA0649 gene on chromosome 9 and corresponds to two small CpG islands in the open reading frame of the ancestral gene. It is methylated on the maternal chromosome 13 and acts as a weak promoter for an alternative RB1 transcript on the paternal chromosome 13. In four other KIAA0649 pseudogene copies, which are located on chromosome 22, the two CpG islands have deteriorated and the CpG dinucleotides are fully methylated. By analysing allelic RB1 transcript levels in blood cells, as well as in hypermethylated and 5-aza-2'-deoxycytidine-treated lymphoblastoid cells, we have found that differential methylation of the CpG island skews RB1 gene expression in favor of the maternal allele. Thus, RB1 is imprinted in the same direction as CDKN1C, which operates upstream of RB1. The imprinting of two components of the same pathway indicates that there has been strong evolutionary selection for maternal inhibition of cell proliferation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.pgen.1000790DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2791201PMC
December 2009

Identification of a mutation in exon 27 of the RB1 gene associated with incomplete penetrance retinoblastoma.

Fam Cancer 2009 29;8(1):55-8. Epub 2008 May 29.

Institut für Humangenetik, Universitätsklinikum Essen, Hufelandstr. 55, Essen, 45122, Germany.

Retinoblastoma (Rb) is initiated by germline mutations in the RB1 gene. Up to date, no mutation was identified in exons 26 and 27. We have identified a 2 bp frameshift insertion in exon 27 of the RB1 gene (RBg.177008_177009dup) in a boy with unilateral Rb and his healthy father that has occurred de novo on the allele transmitted by the father's father. RT-PCR showed that the mutant +2 bp transcript is present in RNA from peripheral leukocytes after short-term culture. The level of the mutant transcript was low compared to the normal transcript indicating abnormal expression of the variant allele. The mutant transcript was further reduced after puromycin treatment suggesting that NMD is not involved. Although oncogenic mutations in the terminal exons of the RB1 gene are rare molecular testing is important as those terminal mutations can be associated with incomplete penetrance and cause high recurrence risk in family members.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10689-008-9198-4DOI Listing
April 2009

Expanded clinical spectrum of spondylocarpotarsal synostosis syndrome and possible manifestation in a heterozygous father.

Am J Med Genet A 2008 Mar;146A(6):779-83

Institut für Humangenetik, Universitätsklinikum Essen, Essen, Germany.

We report on a 5-year-old boy with spondylocarpotarsal synostosis (SCT) syndrome who presents with disproportionate short stature, thoracic scoliosis, pes planus, dental enamel hypoplasia, unilateral conductive hearing loss and mild facial dysmorphisms. Radiographs showed abnormal segmentation of the spine with block vertebrae and carpal synostosis. In addition to the typical phenotype of SCT syndrome, he showed pronounced delay of carpal bone age and bilateral epiphyseal dysplasia of the proximal femora. The patient's father has mild short stature and unilateral hip dysplasia. Molecular studies of the filamin B gene (FLNB) revealed a homozygous mutation in the index patient while both parents were heterozygous for the mutation. In this report we expand the phenotype of SCT syndrome in a patient with a causal FLNB mutation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ajmg.a.32230DOI Listing
March 2008

Estrogen receptor {beta}1 exerts antitumoral effects on SK-OV-3 ovarian cancer cells.

J Endocrinol 2007 Jun;193(3):421-33

Department of Obstetrics and Gynecology, Klinik für Frauenheilkunde und Geburtshilfe, University of Regensburg, Landshuter Strasse 65, 93053 Regensburg, Germany.

Estrogen receptor (ER) beta1 and its splice variants are expressed both in ovary and ovarian cancer. We studied the role of ERbeta1 and two of its splice variants in regulation of gene expression, cellular proliferation, apoptosis, and migration of an ovarian cancer cell line. In this study, we transfected SK-OV-3 ovarian cancer cells with vectors coding for ERbeta1 or its splice variants ERbeta-delta125 and ERbeta-delta1256, and tested their response to estrogen and tamoxifen in comparison with the untransfected cells. Heterologous expression of ERbeta1, but not of the exon-deleted ERbeta variants resulted in notably slower cell growth of SK-OV-3 ovarian cancer cells, an effect accompanied by more than tenfold increase of cyclin-dependent kinase inhibitor p21(WAF1) transcript levels and a significant reduction of cyclin A2 mRNA levels. SK-OV-3 cells stably overexpressing ERbeta1 ligand independently also exhibited an increased apoptosis rate and a significantly decreased motility, an effect accompanied by upregulation of fibulin 1c. Our data demonstrate that ERbeta1, but not the exon-deleted isoforms tested exerts multiple antitumoral effects on SK-OV-3 ovarian cancer cells even in the absence of estradiol or functional ERalpha.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1677/JOE-07-0087DOI Listing
June 2007

A novel gene for Usher syndrome type 2: mutations in the long isoform of whirlin are associated with retinitis pigmentosa and sensorineural hearing loss.

Hum Genet 2007 Apr 15;121(2):203-11. Epub 2006 Dec 15.

Institute of Human Genetics, University Hospital of Cologne, Kerpener Str. 34, 50931 Cologne, Germany.

Usher syndrome is an autosomal recessive condition characterized by sensorineural hearing loss, variable vestibular dysfunction, and visual impairment due to retinitis pigmentosa (RP). The seven proteins that have been identified for Usher syndrome type 1 (USH1) and type 2 (USH2) may interact in a large protein complex. In order to identify novel USH genes, we followed a candidate strategy, assuming that mutations in proteins interacting with this "USH network" may cause Usher syndrome as well. The DFNB31 gene encodes whirlin, a PDZ scaffold protein with expression in both hair cell stereocilia and retinal photoreceptor cells. Whirlin represents an excellent candidate for USH2 because it binds to Usherin (USH2A) and VLGR1b (USH2C). Genotyping of microsatellite markers specific for the DFNB31 gene locus on chromosome 9q32 was performed in a German USH2 family that had been excluded for all known USH loci. Patients showed common haplotypes. Sequence analysis of DFNB31 revealed compound heterozygosity for a nonsense mutation, p.Q103X, in exon 1, and a mutation in the splice donor site of exon 2, c.837+1G>A. DFNB31 mutations appear to be a rare cause of Usher syndrome, since no mutations were identified in an additional 96 USH2 patients. While mutations in the C-terminal half of whirlin have previously been reported in non-syndromic deafness (DFNB31), both alterations identified in our USH2 family affect the long protein isoform. We propose that mutations causing Usher syndrome are probably restricted to exons 1-6 that are specific for the long isoform and probably crucial for retinal function. We describe a novel genetic subtype for Usher syndrome, which we named USH2D and which is caused by mutations in whirlin. Moreover, this is the first case of USH2 that is allelic to non-syndromic deafness.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00439-006-0304-0DOI Listing
April 2007

Is there a higher incidence of maternal uniparental disomy 14 [upd(14)mat]? Detection of 10 new patients by methylation-specific PCR.

Am J Med Genet A 2006 Oct;140(19):2039-49

Institut für Humangenetik, Universitätsklinikum Essen, Essen, Germany.

Maternal uniparental disomy for chromosome 14 [upd(14)mat] is associated with a characteristic phenotype including pre- and postnatal growth retardation, muscular hypotonia, feeding problems, motor delay, small hands and feet, precocious puberty and truncal obesity. Patients with upd(14)mat show features overlapping with Prader-Willi syndrome (PWS) and are probably underdiagnosed. Maternal upd(14) is frequently described in carriers of a Robertsonian translocation involving chromosome 14, but is also found in patients with a normal karyotype. Based on the above mentioned criteria we have identified six patients with upd(14)mat including two patients with a normal karyotype, one patient with a de novo Robertsonian translocation (14;21), one patient with a familial Robertsonian translocation (13;14) and two patients with a marker chromosome. In addition, we analyzed a cohort of 33 patients with low birth weight, feeding difficulties and consecutive obesity in whom PWS had been excluded by methylation analysis of SNRPN. In four of these patients (12%) we detected upd(14)mat. For rapid testing of upd(14)mat we analyzed the methylation status of the imprinted MEG3 locus. In conclusion, we recommend considering upd(14)mat in patients with low birth weight, growth retardation, neonatal feeding problems, muscular hypotonia, motor delay, precocious puberty and truncal obesity as well as in patients with a PWS like phenotype presenting with low birth weight, feeding difficulties and obesity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ajmg.a.31414DOI Listing
October 2006

The synaptophysin/synaptobrevin complex dissociates independently of neuroexocytosis.

J Neurochem 2004 Jul;90(1):1-8

Centrum für Anatomie, Charité Universitätsmedizin, Berlin, AG Funktionelle Zellbiologie, Berlin, Germany.

Synaptophysin is one of the most abundant membrane proteins of small synaptic vesicles. In mature nerve terminals it forms a complex with the vesicular membrane protein synaptobrevin, which appears to modulate synaptobrevin's interaction with the plasma membrane-associated proteins syntaxin and SNAP25 to form the SNARE complex as a prerequisite for membrane fusion. Here we show that synaptobrevin is preferentially cleaved by tetanus toxin while bound to synaptophysin or when existing as a homodimer. The synaptophysin/synaptobrevin complex is, however, not affected when neuronal secretion is blocked by botulinum A toxin which cleaves SNAP25. Excessive stimulation with alpha-latrotoxin or Ca(2+)-ionophores dissociates the synaptophysin/synaptobrevin complex and increases the interaction of the other SNARE proteins. The stimulation-induced dissociation of the synaptophysin/synaptobrevin complex is not inhibited by pre-incubating neurones with botulinum A toxin, but depends on extracellular calcium. However, the synaptophysin/synaptobrevin complex cannot be directly dissociated by calcium alone or in combination with magnesium. The dissociation of synaptobrevin from synaptophysin appears to precede its interaction with the other SNARE proteins and does not depend on the final fusion event. This finding further supports the modulatory role the synaptophysin/synaptobrevin complex may play in mature neurones.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1471-4159.2004.02472.xDOI Listing
July 2004

The synaptophysin/synaptobrevin interaction critically depends on the cholesterol content.

J Neurochem 2003 Jan;84(1):35-42

Institut für Anatomie der Charité, Mathematisch-natur-wissenschaftliche Fakultät I, Humboldt Universität zu Berlin, Berlin, Germany.

Synaptophysin interacts with synaptobrevin in membranes of adult small synaptic vesicles. The synaptophysin/synaptobrevin complex promotes synaptobrevin to built up functional SNARE complexes thereby modulating synaptic efficiency. Synaptophysin in addition is a cholesterol-binding protein. Depleting the membranous cholesterol content by filipin or beta-methylcyclodextrin (beta-MCD) decreased the solubility of synaptophysin in Triton X-100 with less effects on synaptobrevin. In small synaptic vesicles from rat brain the synaptophysin/synaptobrevin complex was diminished upon beta-MCD treatment as revealed by chemical cross-linking. Mice with a genetic mutation in the Niemann-Pick C1 gene developing a defect in cholesterol sorting showed significantly reduced amounts of the synaptophysin/synaptobrevin complex compared to their homo- or heterozygous littermates. Finally when using primary cultures of mouse hippocampus the synaptophysin/synaptobrevin complex was down-regulated after depleting the endogenous cholesterol content by the HMG-CoA-reductase inhibitor lovastatin. Alternatively, treatment with cholesterol up-regulated the synaptophysin/synaptobrevin interaction in these cultures. These data indicate that the synaptophysin/synaptobrevin interaction critically depends on a high cholesterol content in the membrane of synaptic vesicles. Variations in the availability of cholesterol may promote or impair synaptic efficiency by interfering with this complex.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1046/j.1471-4159.2003.01258.xDOI Listing
January 2003