Publications by authors named "Yves Sznajer"

56 Publications

Antenatal diagnosis of CHARGE syndrome: Prenatal ultrasound findings and crucial role of fetal dysmorphic signs. About a series of 10 cases and review of literature.

Eur J Med Genet 2021 Apr 2;64(4):104189. Epub 2021 Mar 2.

Center for Human Genetics, Cliniques Universitaires Saint-Luc, UCLouvain, Brussels, Belgium.

Although the prognosis of CHARGE syndrome can be highly variable from mild until severe, final diagnosis is difficult to establish in utero. The aim of our study is to compare antenatal and postnatal findings in a retrospective cohort of 10 successive patients with a positive CHD7 gene variant in order to identify the specific prenatal features for CHARGE syndrome diagnosis. Fetal ultrasound, follow-up and supplementary investigations are collected and compared to postnatal findings. Congenital heart defect (7/10), choanal atresia (7/10) and tracheoesophageal atresia (4/10) are the most frequent fetal anomalies found. Inner and external ear anomalies appear as the keystone (constant features) for prenatal diagnosis of CHARGE syndrome in fetuses with multiple anomalies and normal microarray karyotype. External ear malformations are identified in all cases by 3D ultrasound when carefully evaluated. MRI and temporal bone CT-Scan are second line useful tools to assess the diagnosis when looking for semicircular canal agenesis, arhinencephaly and/or choanal atresia. Before availability of prenatal exome sequencing in clinical routine, present findings lead to the recommendation that fetuses, with congenital heart defect (mainly septal and conotruncal), cleft lip/palate or unexplained polyhydramnios should carefully be screened for clues suggesting CHARGE syndrome using 2D and 3D ultrasound, MRI and temporal bone CT-Scan. When CHARGE syndrome is suspected with normal molecular karyotype, CHD7 gene sequencing must be offered.
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http://dx.doi.org/10.1016/j.ejmg.2021.104189DOI Listing
April 2021

Outcome of publicly funded nationwide first-tier noninvasive prenatal screening.

Genet Med 2021 Feb 9. Epub 2021 Feb 9.

Center for Human Genetics, University Hospitals Leuven-KU Leuven, Leuven, Belgium.

Purpose: Noninvasive prenatal screening (NIPS) using cell-free DNA has transformed prenatal care. Belgium was the first country to implement and fully reimburse NIPS as a first-tier screening test offered to all pregnant women. A consortium consisting of all Belgian genetic centers report the outcome of two years genome-wide NIPS implementation.

Methods: The performance for the common trisomies and for secondary findings was evaluated based on 153,575 genome-wide NIP tests. Furthermore, the evolution of the number of invasive tests and the incidence of Down syndrome live births was registered.

Results: Trisomies 21, 18, and 13 were detected in respectively 0.32%, 0.07%, and 0.06% of cases, with overall positive predictive values (PPVs) of 92.4%, 84.6%, and 43.9%. Rare autosomal trisomies and fetal segmental imbalances were detected in respectively 0.23% and 0.07% of cases with PPVs of 4.1% and 47%. The number of invasive obstetric procedures decreased by 52%. The number of trisomy 21 live births dropped to 0.04%.

Conclusion: Expanding the scope of NIPS beyond trisomy 21 fetal screening allows the implementation of personalized genomic medicine for the obstetric population. This genome-wide NIPS approach has been embedded successfully in prenatal genetic care in Belgium and might serve as a framework for other countries offering NIPS.
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http://dx.doi.org/10.1038/s41436-021-01101-4DOI Listing
February 2021

Novel RPL13 Variants and Variable Clinical Expressivity in a Human Ribosomopathy With Spondyloepimetaphyseal Dysplasia.

J Bone Miner Res 2021 Feb 13;36(2):283-297. Epub 2020 Oct 13.

Department of Molecular Medicine and Surgery and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.

Spondyloepimetaphyseal dysplasias (SEMDs) are a heterogeneous group of disorders with variable growth failure and skeletal impairments affecting the spine and long bone epiphyses and metaphyses. Here we report on four unrelated families with SEMD in which we identified two monoallelic missense variants and one monoallelic splice site variant in RPL13, encoding the ribosomal protein eL13. In two out of four families, we observed autosomal dominant inheritance with incomplete penetrance and variable clinical expressivity; the phenotypes of the mutation-positive subjects ranged from normal height with or without hip dysplasia to severe SEMD with severe short stature and marked skeletal dysplasia. In vitro studies on patient-derived dermal fibroblasts harboring RPL13 missense mutations demonstrated normal eL13 expression, with proper subcellular localization but reduced colocalization with eL28 (p < 0.001). Cellular functional defects in fibroblasts from mutation-positive subjects indicated a significant increase in the ratio of 60S subunits to 80S ribosomes (p = 0.007) and attenuated global translation (p = 0.017). In line with the human phenotype, our rpl13 mutant zebrafish model, generated by CRISPR-Cas9 editing, showed cartilage deformities at embryonic and juvenile stages. These findings extend the genetic spectrum of RPL13 mutations causing this novel human ribosomopathy with variable skeletal features. Our study underscores for the first time incomplete penetrance and broad phenotypic variability in SEMD-RPL13 type and confirms impaired ribosomal function. Furthermore, the newly generated rpl13 mutant zebrafish model corroborates the role of eL13 in skeletogenesis. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR)..
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http://dx.doi.org/10.1002/jbmr.4177DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7988564PMC
February 2021

Defining a Centiloid scale threshold predicting long-term progression to dementia in patients attending the memory clinic: an [F] flutemetamol amyloid PET study.

Eur J Nucl Med Mol Imaging 2021 Jan 29;48(1):302-310. Epub 2020 Jun 29.

Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium.

Purpose: To evaluate cerebral amyloid-β(Aβ) pathology in older adults with cognitive complaints, visual assessment of PET images is approved as the routine method for image interpretation. In research studies however, Aβ-PET semi-quantitative measures are associated with greater risk of progression to dementia; but until recently, these measures lacked standardization. Therefore, the Centiloid scale, providing standardized Aβ-PET semi-quantitation, was recently validated. We aimed to determine the predictive values of visual assessments and Centiloids in non-demented patients, using long-term progression to dementia as our standard of truth.

Methods: One hundred sixty non-demented participants (age, 54-86) were enrolled in a monocentric [F] flutemetamol Aβ-PET study. Flutemetamol images were interpreted visually following the manufacturers recommendations. SUVr values were converted to the Centiloid scale using the GAAIN guidelines. Ninety-eight persons were followed until dementia diagnosis or were clinically stable for a median of 6 years (min = 4.0; max = 8.0). Twenty-five patients with short follow-up (median = 2.0 years; min = 0.8; max = 3.9) and 37 patients with no follow-up were excluded. We computed ROC curves predicting subsequent dementia using baseline PET data and calculated negative (NPV) and positive (PPV) predictive values.

Results: In the 98 participants with long follow-up, Centiloid = 26 provided the highest overall predictive value = 87% (NPV = 85%, PPV = 88%). Visual assessment corresponded to Centiloid = 40, which predicted dementia with an overall predictive value = 86% (NPV = 81%, PPV = 92%). Inclusion of the 25 patients who only had a 2-year follow-up decreased the PPV = 67% (NPV = 88%), reflecting the many positive cases that did not progress to dementia after short follow-ups.

Conclusion: A Centiloid threshold = 26 optimally predicts progression to dementia 6 years after PET. Visual assessment provides similar predictive value, with higher specificity and lower sensitivity.

Trial Registration: Eudra-CT number: 2011-001756-12.
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http://dx.doi.org/10.1007/s00259-020-04942-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7835306PMC
January 2021

Expanding the genotypic and phenotypic spectrum of severe serine biosynthesis disorders.

Hum Mutat 2020 Sep 15;41(9):1615-1628. Epub 2020 Jul 15.

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

Serine biosynthesis disorders comprise a spectrum of very rare autosomal recessive inborn errors of metabolism with wide phenotypic variability. Neu-Laxova syndrome represents the most severe expression and is characterized by multiple congenital anomalies and pre- or perinatal lethality. Here, we present the mutation spectrum and a detailed phenotypic analysis in 15 unrelated families with severe types of serine biosynthesis disorders. We identified likely disease-causing variants in the PHGDH and PSAT1 genes, several of which have not been reported previously. Phenotype analysis and a comprehensive review of the literature corroborates the evidence that serine biosynthesis disorders represent a continuum with varying degrees of phenotypic expression and suggest that even gradual differences at the severe end of the spectrum may be correlated with particular genotypes. We postulate that the individual residual enzyme activity of mutant proteins is the major determinant of the phenotypic variability, but further functional studies are needed to explore effects at the enzyme protein level.
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http://dx.doi.org/10.1002/humu.24067DOI Listing
September 2020

Phenotype description in KIF5C gene hot-spot mutations responsible for malformations of cortical development (MCD).

Eur J Med Genet 2020 Sep 18;63(9):103991. Epub 2020 Jun 18.

Center for Human Genetics, Cliniques Universitaires Saint Luc, UCLouvain, Brussels, Belgium. Electronic address:

Malformations of cortical development (MCD) represent a large group of brain cortical anomalies characterized by distinctive MRI findings. This 'radiologically-based' classification required re evaluation over time on identified underlying mechanisms (cytogenetic and/or molecular). The understanding of genotype findings (nature of cytogenetic/molecular mutation, cellular pathways consequences, timing, …) draw line of evidence on these distinctive group of conditions whereas sometimes precise and constant recurrent genotype/phenotype correlation may not be present. The clinical diagnosis of MCD is often difficult due to variability and rarity of individual types of malformations. Recent studies have established a relationship between lissencephaly and pathogenic variants in genes involved in the kinesin/tubulin pathways, as the KIF5C gene. Pathogenic variants in the KIF5C gene are a more recently discovered cause of severe developmental delay with epilepsy, characterized by specific malformation of cortical development such as pachygyria. Only seven children have been described to date. We report the natural history of a sixteen years old patient identified carrier of a KIF5C gene mutation who developed infantile epilepsy. We then gather phenotype description and molecular results of all reported patients so far in order to better define this entity.
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http://dx.doi.org/10.1016/j.ejmg.2020.103991DOI Listing
September 2020

Prenatally detected copy number variants in a national cohort: A postnatal follow-up study.

Prenat Diagn 2020 09 24;40(10):1272-1283. Epub 2020 Jun 24.

Center for Medical Genetics, Universiteit Antwerpen, Antwerpen, Belgium.

Objective: Belgian genetic centers established a database containing data on all chromosomal microarrays performed in a prenatal context. A study was initiated to evaluate postnatal development in children diagnosed prenatally with a non-benign copy number variant (CNV).

Methods: All children diagnosed with a prenatally detected non-benign CNV in a Belgian genetic center between May 2013 and February 2015 were included in the patient population. The control population consisted of children who had undergone an invasive procedure during pregnancy, with no or only benign CNVs. Child development was evaluated at 36 months using three (3) questionnaires: Ages and Stages Questionnaire Third edition, Ages and Stages Questionnaire Social-Emotional Second Edition and a general questionnaire.

Results: A significant difference in communication and personal-social development was detected between children with a reported susceptibility CNV and both children with an unreported susceptibility CNV and the control population. The outcome of children with a particular CNV is discussed in a case-by-case manner.

Conclusion: Our postnatal follow-up project of children with a prenatally detected non-benign CNV is the first nationwide project of its kind. A higher number of cases for each CNV category is however needed to confirm our findings.
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http://dx.doi.org/10.1002/pd.5751DOI Listing
September 2020

Null variants and deletions in BRWD3 cause an X-linked syndrome of mild-moderate intellectual disability, macrocephaly, and obesity: A series of 17 patients.

Am J Med Genet C Semin Med Genet 2019 12 12;181(4):638-643. Epub 2019 Nov 12.

South West Thames Regional Genetics Service, St George's University NHS Foundation Trust, London, UK.

BRWD3 has been described as a cause of X-linked intellectual disability, but relatively little is known about the specific phenotype. We report the largest BRWD3 patient series to date, comprising 17 males with 12 distinct null variants and 2 partial gene deletions. All patients presented with intellectual disability, which was classified as moderate (65%) or mild (35%). Behavioral issues were present in 75% of patients, including aggressive behavior, attention deficit/hyperactivity and/or autistic spectrum disorders. Mean head circumference was +2.8 SD (2.8 standard deviations above the mean), and mean BMI was +2.0 SD (in the context of a mean height of +1.3 SD), indicating a predominant macrocephaly/obesity phenotype. Shared facial features included a tall chin, prognathism, broad forehead, and prominent supraorbital ridge. Additional features, reported in a minority (<30%) of patients included cryptorchidism, neonatal hypotonia, and small joint hypermobility. This study delineates the clinical features associated with BRWD3 null variants and partial gene deletions, and suggests that BRWD3 should be included in the differential diagnosis of patients with an overgrowth-intellectual disability (OGID) phenotype, particularly in male patients with a mild or moderate intellectual disability associated with macrocephaly and/or obesity.
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http://dx.doi.org/10.1002/ajmg.c.31750DOI Listing
December 2019

Antenatal diagnosis of cardio-facio-cutaneous syndrome: Prenatal characteristics and contribution of fetal facial dysmorphic signs in utero. About a case and review of literature.

Eur J Obstet Gynecol Reprod Biol 2019 Sep 16;240:232-241. Epub 2019 Jul 16.

Center for Human Genetics, Saint-Luc University Hospital, UCL, Brussels, Belgium.

Antenatal diagnosis of cardio-facio-cutaneous syndrome: prenatal characteristics and contribution of fetal facial dysmorphic signs in utero. This paper is a case study and review of literature. "RASopathies" is the term coined for a group of genetic diseases that share modulation inside the MAPKinase pathway. Mutations inside the coding sequence of any of these genes may be responsible for the upregulation of the RAS pathway, leading on the clinical level to Type 1 Neurofibromatosis (NF1), Noonan syndrome (NS), Costello syndrome (CS), Multiple Lentigines, Loose Anagen Hair syndrome, Cardio-Facio-Cutaneous syndrome (CFCS), and, more recently, Legius syndrome. While the postnatal presentation of this group is well-known, prenatal findings are less well recognized. The presence of a RASopathy during the prenatal period can be suspected on account of non-specific abnormalities: polyhydramnios, cystic hygroma or high nuchal translucency, macrosomia with proportionate short long bones, macrocephaly, renal, lymphatic, or cardiac defects. The current case report underlines the characteristic dysmorphic facial features on 3D-ultrasound (hypertelorism, down-slanting palpebral fissures, a long and marked philtrum, and low-set posteriorly rotated ears) that allow for a "RASopathy" to be postulated. After detecting a copy number variation (CNV) absence on a CGH array, we performed a RASopathy gene panel analysis, which identified a so-far unreported heterozygous de novo mutation in the BRAF gene (namely NM_004333.4 : c.1396 G > C ; p.Gly466Arg). Genetic counseling has, therefore, focused on the diagnosis of a RASopathy and predictable phenotype of CFCS, a distinct entity characterized by an increased risk of intellectual disability and early-onset feeding problems. We suggest that a more detailed prenatal facial evaluation should be performed in fetuses presenting high nuchal thickness, heart defects, or unusual findings, along with the absence of a CNV on a CGH array. Due to the dysmorphic facial features, targeted RASopathy genes are presumed to likely to be responsible for NS, CFCS, and CS.
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http://dx.doi.org/10.1016/j.ejogrb.2019.06.035DOI Listing
September 2019

PEDIA: prioritization of exome data by image analysis.

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

Institute of Genomic Statistics and Bioinformatics, University of Bonn, Bonn, Germany.

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

Panel-Based Exome Sequencing for Neuromuscular Disorders as a Diagnostic Service.

J Neuromuscul Dis 2019 ;6(2):241-258

Department of Neurology, Donders Institute for Brain, Cognition, and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands.

Background: Neuromuscular disorders (NMDs) are clinically and genetically heterogeneous. Accurate molecular genetic diagnosis can improve clinical management, provides appropriate genetic counseling and testing of relatives, and allows potential therapeutic trials.

Objective: To establish the clinical utility of panel-based whole exome sequencing (WES) in NMDs in a population with children and adults with various neuromuscular symptoms.

Methods: Clinical exome sequencing, followed by diagnostic interpretation of variants in genes associated with NMDs, was performed in a cohort of 396 patients suspected of having a genetic cause with a variable age of onset, neuromuscular phenotype, and inheritance pattern. Many had previously undergone targeted gene testing without results.

Results: Disease-causing variants were identified in 75/396 patients (19%), with variants in the three COL6-genes (COL6A1, COL6A2 and COL6A3) as the most common cause of the identified muscle disorder, followed by variants in the RYR1 gene. Together, these four genes account for almost 25% of cases in whom a definite genetic cause was identified. Furthermore, likely pathogenic variants and/or variants of uncertain significance were identified in 95 of the patients (24%), in whom functional and/or segregation analysis should be used to confirm or reject the pathogenicity. In 18% of the cases with a disease-causing variant of which we received additional clinical information, we identified a genetic cause in genes of which the associated phenotypes did not match that of the patients. Hence, the advantage of panel-based WES is its unbiased approach.

Conclusion: Whole exome sequencing, followed by filtering for NMD genes, offers an unbiased approach for the genetic diagnostics of NMD patients. This approach could be used as a first-tier test in neuromuscular disorders with a high suspicion of a genetic cause. With uncertain results, functional testing and segregation analysis are needed to complete the evidence.
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http://dx.doi.org/10.3233/JND-180376DOI Listing
December 2019

ABCA4-associated disease as a model for missing heritability in autosomal recessive disorders: novel noncoding splice, cis-regulatory, structural, and recurrent hypomorphic variants.

Genet Med 2019 08 23;21(8):1761-1771. Epub 2019 Jan 23.

Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium.

Purpose: ABCA4-associated disease, a recessive retinal dystrophy, is hallmarked by a large proportion of patients with only one pathogenic ABCA4 variant, suggestive for missing heritability.

Methods: By locus-specific analysis of ABCA4, combined with extensive functional studies, we aimed to unravel the missing alleles in a cohort of 67 patients (p), with one (p = 64) or no (p = 3) identified coding pathogenic variants of ABCA4.

Results: We identified eight pathogenic (deep-)intronic ABCA4 splice variants, of which five are novel and six structural variants, four of which are novel, including two duplications. Together, these variants account for the missing alleles in 40.3% of patients. Furthermore, two novel variants with a putative cis-regulatory effect were identified. The common hypomorphic variant c.5603A>T p.(Asn1868Ile) was found as a candidate second allele in 43.3% of patients. Overall, we have elucidated the missing heritability in 83.6% of our cohort. In addition, we successfully rescued three deep-intronic variants using antisense oligonucleotide (AON)-mediated treatment in HEK 293-T cells and in patient-derived fibroblast cells.

Conclusion: Noncoding pathogenic variants, novel structural variants, and a common hypomorphic allele of the ABCA4 gene explain the majority of unsolved cases with ABCA4-associated disease, rendering this retinopathy a model for missing heritability in autosomal recessive disorders.
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http://dx.doi.org/10.1038/s41436-018-0420-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6752479PMC
August 2019

The Belgian MicroArray Prenatal (BEMAPRE) database: A systematic nationwide repository of fetal genomic aberrations.

Prenat Diagn 2018 12 14;38(13):1120-1128. Epub 2018 Nov 14.

Center for Medical Genetics, Universiteit Antwerpen, Antwerp, Belgium.

Objective: With the replacement of karyotyping by chromosomal microarray (CMA) in invasive prenatal diagnosis, new challenges have arisen. By building a national database, we standardize the classification and reporting of prenatally detected copy number variants (CNVs) across Belgian genetic centers. This database, which will link genetic and ultrasound findings with postnatal development, forms a unique resource to investigate the pathogenicity of variants of uncertain significance and to refine the phenotypic spectrum of pathogenic and susceptibility CNVs.

Methods: The Belgian MicroArray Prenatal (BEMAPRE) consortium is a collaboration of all genetic centers in Belgium. We collected data from all invasive prenatal procedures performed between May 2013 and July 2016.

Results: In this three-year period, 13 266 prenatal CMAs were performed. By national agreement, a limited number of susceptibility CNVs and no variants of uncertain significance were reported. Added values for using CMA versus conventional karyotyping were 1.8% in the general invasive population and 2.7% in cases with an ultrasound anomaly. Of the reported CNVs, 31.5% would have remained undetected with non-invasive prenatal test as the first-tier test.

Conclusion: The establishment of a national database for prenatal CNV data allows for a uniform reporting policy and the investigation of the prenatal and postnatal genotype-phenotype correlation.
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http://dx.doi.org/10.1002/pd.5373DOI Listing
December 2018

Familial Forms of Cushing Syndrome in Primary Pigmented Nodular Adrenocortical Disease Presenting with Short Stature and Insidious Symptoms: A Clinical Series.

Horm Res Paediatr 2018 15;89(6):423-433. Epub 2018 Jun 15.

Pediatric Endocrinology Unit, Cliniques universitaires Saint Luc, Université Catholique de Louvain, Brussels, Belgium.

Cushing syndrome (CS) is a rare disease in children, frequently associated with subtle or periodic symptoms that may delay its diagnosis. Weight gain and growth failure, the hallmarks of hypercortisolism in pediatrics, may be inconsistent, especially in ACTH-independent forms of CS. Primary pigmented nodular adrenocortical disease (PPNAD) is the rarest form of ACTH-independent CS, and can be associated with endocrine and nonendocrine tumors, forming the Carney complex (CNC). Recently, phenotype/genotype correlations have been described with particular forms of CNC where PPNAD is isolated or associated only with skin lesions. We present four familial series of CS due to isolated PPNAD, and compare them to available data from the literature. We discuss the clinical and molecular findings, and underline challenges in diagnosing PPNAD in childhood.
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http://dx.doi.org/10.1159/000488761DOI Listing
November 2018

Improved diagnosis in nonimmune hydrops fetalis using a standardized algorithm.

Prenat Diagn 2018 04 23;38(5):337-343. Epub 2018 Mar 23.

Centre for Human Genetics, Cliniques Universitaires St. Luc, UCL, Brussels, Belgium.

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http://dx.doi.org/10.1002/pd.5243DOI Listing
April 2018

Patient with confirmed LEOPARD syndrome developing multiple melanoma.

Dermatol Pract Concept 2018 Jan 31;8(1):59-62. Epub 2018 Jan 31.

Department of Dermatology, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Brussels, Belgium.

LEOPARD syndrome, also known as Gorlin syndrome II, cardiocutaneous syndrome, lentiginosis profusa syndrome, Moynahan syndrome, was more recently coined as Noonan syndrome with multiple lentigines (NSML), inside the RASopathies. Historically, the acronym LEOPARD refers to the presence of distinctive clinical features such as: lentigines (L), electrocardiographic/conduction abnormalities (E), ocular hypertelorism (O), pulmonary stenosis (P), genital abnormalities (A), retardation of growth (R), and sensorineural deafness (D). This condition is identified in 85% of patients with phenotype hallmarks caused by presence a germline point mutation in PTPN11 gene. Association of melanoma to NSML seems to be rare: to our knowledge, two patients so far were reported in the literature. We herein present a patient diagnosed with LEOPARD syndrome, in whom molecular investigation confirmed the presence of the c.1403C>T mutation in exon 12 of the PTPN11 gene, who developed four superficial spreading melanomas and three atypical lentiginous hyperplasias. Three of the melanomas were achromic or hypochromic, three were in situ, and one had a Breslow index under 0.5 mm. Dermoscopic examination showed some characteristic white structures in most of the lesions, which were a signature pattern and a key for the diagnosis.
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http://dx.doi.org/10.5826/dpc.0801a14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5808376PMC
January 2018

Childhood hearing loss is a key feature of CAPOS syndrome: A case report.

Int J Pediatr Otorhinolaryngol 2018 Jan 22;104:191-194. Epub 2017 Nov 22.

Pediatric Neurology Unit, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Brussels, Belgium.

CAPOS syndrome (cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss) is a rare neurological disorder, recently associated with the c.2452G > A hotspot mutation in the ATP1A3 gene, with sensorineural hearing loss as a prominent feature. We herein report on a girl who has experienced hearing loss for three years following an initial encephalitic episode when aged 15 months old. CAPOS was diagnosed only when she was six years old by targeted testing whilst she displayed optic atrophy, cerebellar signs and areflexia. CAPOS syndrome should be considered in the differential diagnosis of acquired childhood deafness, prompting clinicians to search for associated neurological features.
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http://dx.doi.org/10.1016/j.ijporl.2017.11.022DOI Listing
January 2018

Autosomal recessive primary microcephaly due to ASPM mutations: An update.

Hum Mutat 2018 03 16;39(3):319-332. Epub 2018 Jan 16.

PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France.

Autosomal recessive microcephaly or microcephaly primary hereditary (MCPH) is a genetically heterogeneous neurodevelopmental disorder characterized by a reduction in brain volume, indirectly measured by an occipitofrontal circumference (OFC) 2 standard deviations or more below the age- and sex-matched mean (-2SD) at birth and -3SD after 6 months, and leading to intellectual disability of variable severity. The abnormal spindle-like microcephaly gene (ASPM), the human ortholog of the Drosophila melanogaster "abnormal spindle" gene (asp), encodes ASPM, a protein localized at the centrosome of apical neuroprogenitor cells and involved in spindle pole positioning during neurogenesis. Loss-of-function mutations in ASPM cause MCPH5, which affects the majority of all MCPH patients worldwide. Here, we report 47 unpublished patients from 39 families carrying 28 new ASPM mutations, and conduct an exhaustive review of the molecular, clinical, neuroradiological, and neuropsychological features of the 282 families previously reported (with 161 distinct ASPM mutations). Furthermore, we show that ASPM-related microcephaly is not systematically associated with intellectual deficiency and discuss the association between the structural brain defects (strong reduction in cortical volume and surface area) that modify the cortical map of these patients and their cognitive abilities.
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http://dx.doi.org/10.1002/humu.23381DOI Listing
March 2018

A panel study on patients with dominant cerebellar ataxia highlights the frequency of channelopathies.

Brain 2017 Jun;140(6):1579-1594

INSERM U 1127, 75013, Paris, France.

Autosomal dominant cerebellar ataxias have a marked heterogeneous genetic background, with mutations in 34 genes identified so far. This large amount of implicated genes accounts for heterogeneous clinical presentations, making genotype-phenotype correlations a major challenge in the field. While polyglutamine ataxias, linked to CAG repeat expansions in genes such as ATXN1, ATXN2, ATXN3, ATXN7, CACNA1A and TBP, have been extensively characterized in large cohorts, there is a need for comprehensive assessment of frequency and phenotype of more 'conventional' ataxias. After exclusion of CAG/polyglutamine expansions in spinocerebellar ataxia genes in 412 index cases with dominantly inherited cerebellar ataxias, we aimed to establish the relative frequencies of mutations in other genes, with an approach combining panel sequencing and TaqMan® polymerase chain reaction assay. We found relevant genetic variants in 59 patients (14.3%). The most frequently mutated were channel genes [CACNA1A (n = 16), KCND3 (n = 4), KCNC3 (n = 2) and KCNA1 (n = 2)]. Deletions in ITPR1 (n = 11) were followed by biallelic variants in SPG7 (n = 9). Variants in AFG3L2 (n = 7) came next in frequency, and variants were rarely found in STBN2 (n = 2), ELOVL5, FGF14, STUB1 and TTBK2 (n = 1 each). Interestingly, possible risk factor variants were detected in SPG7 and POLG. Clinical comparisons showed that ataxias due to channelopathies had a significantly earlier age at onset with an average of 24.6 years, versus 40.9 years for polyglutamine expansion spinocerebellar ataxias and 37.8 years for SPG7-related forms (P = 0.001). In contrast, disease duration was significantly longer in the former (20.5 years versus 9.3 and 13.7, P=0.001), though for similar functional stages, indicating slower progression of the disease. Of interest, intellectual deficiency was more frequent in channel spinocerebellar ataxias, while cognitive impairment in adulthood was similar among the three groups. Similar differences were found among a single gene group, comparing 23 patients with CACNA1A expansions (spinocerebellar ataxia 6) to 22 patients with CACNA1A point mutations, which had lower average age at onset (25.2 versus 47.3 years) with longer disease duration (18.7 versus 10.9), but lower severity indexes (0.39 versus 0.44), indicating slower progression of the disease. In conclusion, we identified relevant genetic variations in up to 15% of cases after exclusion of polyglutamine expansion spinocerebellar ataxias, and confirmed CACNA1A and SPG7 as major ataxia genes. We could delineate firm genotype-phenotype correlations that are important for genetic counselling and of possible prognostic value.
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http://dx.doi.org/10.1093/brain/awx081DOI Listing
June 2017

EDNRB mutations cause Waardenburg syndrome type II in the heterozygous state.

Hum Mutat 2017 05 15;38(5):581-593. Epub 2017 Mar 15.

INSERM U955, IMRB, Equipe 6, Créteil, France.

Waardenburg syndrome (WS) is a genetic disorder characterized by sensorineural hearing loss and pigmentation anomalies. The clinical definition of four WS types is based on additional features due to defects in structures mostly arising from the neural crest, with type I and type II being the most frequent. While type I is tightly associated to PAX3 mutations, WS type II (WS2) remains partly enigmatic with mutations in known genes (MITF, SOX10) accounting for only 30% of the cases. We performed exome sequencing in a WS2 index case and identified a heterozygous missense variation in EDNRB. Interestingly, homozygous (and very rare heterozygous) EDNRB mutations are already described in type IV WS (i.e., in association with Hirschsprung disease [HD]) and heterozygous mutations in isolated HD. Screening of a WS2 cohort led to the identification of an overall of six heterozygous EDNRB variations. Clinical phenotypes, pedigrees and molecular segregation investigations unraveled a dominant mode of inheritance with incomplete penetrance. In parallel, cellular and functional studies showed that each of the mutations impairs the subcellular localization of the receptor or induces a defective downstream signaling pathway. Based on our results, we now estimate EDNRB mutations to be responsible for 5%-6% of WS2.
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http://dx.doi.org/10.1002/humu.23206DOI Listing
May 2017

Neurobehavioural vulnerability and autistic traits in RASopathies.

Authors:
Yves Sznajer

Dev Med Child Neurol 2017 05 22;59(5):461. Epub 2017 Feb 22.

Centre for Human Genetics, Cliniques universitaires St Luc - UCL, Brussels, Belgium.

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http://dx.doi.org/10.1111/dmcn.13409DOI Listing
May 2017

Mutations in sphingosine-1-phosphate lyase cause nephrosis with ichthyosis and adrenal insufficiency.

J Clin Invest 2017 Mar 6;127(3):912-928. Epub 2017 Feb 6.

Steroid-resistant nephrotic syndrome (SRNS) causes 15% of chronic kidney disease cases. A mutation in 1 of over 40 monogenic genes can be detected in approximately 30% of individuals with SRNS whose symptoms manifest before 25 years of age. However, in many patients, the genetic etiology remains unknown. Here, we have performed whole exome sequencing to identify recessive causes of SRNS. In 7 families with SRNS and facultative ichthyosis, adrenal insufficiency, immunodeficiency, and neurological defects, we identified 9 different recessive mutations in SGPL1, which encodes sphingosine-1-phosphate (S1P) lyase. All mutations resulted in reduced or absent SGPL1 protein and/or enzyme activity. Overexpression of cDNA representing SGPL1 mutations resulted in subcellular mislocalization of SGPL1. Furthermore, expression of WT human SGPL1 rescued growth of SGPL1-deficient dpl1Δ yeast strains, whereas expression of disease-associated variants did not. Immunofluorescence revealed SGPL1 expression in mouse podocytes and mesangial cells. Knockdown of Sgpl1 in rat mesangial cells inhibited cell migration, which was partially rescued by VPC23109, an S1P receptor antagonist. In Drosophila, Sply mutants, which lack SGPL1, displayed a phenotype reminiscent of nephrotic syndrome in nephrocytes. WT Sply, but not the disease-associated variants, rescued this phenotype. Together, these results indicate that SGPL1 mutations cause a syndromic form of SRNS.
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http://dx.doi.org/10.1172/JCI89626DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5330730PMC
March 2017

"Serpentine-like syndrome"-A very rare multiple malformation syndrome characterised by brachioesophagus and vertebral anomalies.

Eur J Med Genet 2017 Feb 9;60(2):100-104. Epub 2016 Nov 9.

Centre de Génétique Humaine, Cliniques Universitaires St. Luc, U.C.L., Brussels.

"Serpentine-like syndrome" is a severe and rare association of multiple congenital malformations, characterised by brachioesophagus, secondary intrathoracic stomach, and vertebral anomalies. Other associated anomalies have been described, such as malposition and herniation of abdominal organs. We report the natural history of a baby girl born at 29 weeks of gestation with intra uterine growth restriction, short neck, large rachischisis from cervical to thoracic spine, a very short oesophagus, thoracic stomach associated with a midline diaphragmatic hernia, malrotated gut and median cleft lip. Most of these anomalies were detected antenatally. Molecular karyotype was normal. She died at age 12 days. To our knowledge, the present patient represents the 8th report of a case of "Serpentine-like syndrome". Brachioesophagus and congenital vertebral anomalies, in particular rachischisis, are the cardinal features of this condition. All reported cases have been sporadic and the cause is still unknown. We believe that the specificity of the presentation as well as the similarities between available descriptions of patients suggests a common, yet to identify, molecular cause, possibly involving a developmental "toolkit"/homeobox gene or related pathways.
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http://dx.doi.org/10.1016/j.ejmg.2016.11.002DOI Listing
February 2017

'De novo' Col4A2 mutation in a patient with migraine, leukoencephalopathy, and small carotid aneurysms.

J Neurol 2016 Nov 13;263(11):2327-2329. Epub 2016 Sep 13.

Center for Human Genetic, Cliniques Universitaires St-Luc, Université Catholique de Louvain, 10 Av. Hippocrate, 1200, Brussels, Belgium.

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http://dx.doi.org/10.1007/s00415-016-8280-3DOI Listing
November 2016

Pathogenetics of alveolar capillary dysplasia with misalignment of pulmonary veins.

Authors:
Przemyslaw Szafranski Tomasz Gambin Avinash V Dharmadhikari Kadir Caner Akdemir Shalini N Jhangiani Jennifer Schuette Nihal Godiwala Svetlana A Yatsenko Jessica Sebastian Suneeta Madan-Khetarpal Urvashi Surti Rosanna G Abellar David A Bateman Ashley L Wilson Melinda H Markham Jill Slamon Fernando Santos-Simarro María Palomares Julián Nevado Pablo Lapunzina Brian Hon-Yin Chung Wai-Lap Wong Yoyo Wing Yiu Chu Gary Tsz Kin Mok Eitan Kerem Joel Reiter Namasivayam Ambalavanan Scott A Anderson David R Kelly Joseph Shieh Taryn C Rosenthal Kristin Scheible Laurie Steiner M Anwar Iqbal Margaret L McKinnon Sara Jane Hamilton Kamilla Schlade-Bartusiak Dawn English Glenda Hendson Elizabeth R Roeder Thomas S DeNapoli Rebecca Okashah Littlejohn Daynna J Wolff Carol L Wagner Alison Yeung David Francis Elizabeth K Fiorino Morris Edelman Joyce Fox Denise A Hayes Sandra Janssens Elfride De Baere Björn Menten Anne Loccufier Lieve Vanwalleghem Philippe Moerman Yves Sznajer Amy S Lay Jennifer L Kussmann Jasneek Chawla Diane J Payton Gael E Phillips Erwin Brosens Dick Tibboel Annelies de Klein Isabelle Maystadt Richard Fisher Neil Sebire Alison Male Maya Chopra Jason Pinner Girvan Malcolm Gregory Peters Susan Arbuckle Melissa Lees Zoe Mead Oliver Quarrell Richard Sayers Martina Owens Charles Shaw-Smith Janet Lioy Eileen McKay Nicole de Leeuw Ilse Feenstra Liesbeth Spruijt Frances Elmslie Timothy Thiruchelvam Carlos A Bacino Claire Langston James R Lupski Partha Sen Edwina Popek Paweł Stankiewicz

Hum Genet 2016 May 12;135(5):569-586. Epub 2016 Apr 12.

Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Rm. R809, Houston, TX, 77030, USA.

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV) is a lethal lung developmental disorder caused by heterozygous point mutations or genomic deletion copy-number variants (CNVs) of FOXF1 or its upstream enhancer involving fetal lung-expressed long noncoding RNA genes LINC01081 and LINC01082. Using custom-designed array comparative genomic hybridization, Sanger sequencing, whole exome sequencing (WES), and bioinformatic analyses, we studied 22 new unrelated families (20 postnatal and two prenatal) with clinically diagnosed ACDMPV. We describe novel deletion CNVs at the FOXF1 locus in 13 unrelated ACDMPV patients. Together with the previously reported cases, all 31 genomic deletions in 16q24.1, pathogenic for ACDMPV, for which parental origin was determined, arose de novo with 30 of them occurring on the maternally inherited chromosome 16, strongly implicating genomic imprinting of the FOXF1 locus in human lungs. Surprisingly, we have also identified four ACDMPV families with the pathogenic variants in the FOXF1 locus that arose on paternal chromosome 16. Interestingly, a combination of the severe cardiac defects, including hypoplastic left heart, and single umbilical artery were observed only in children with deletion CNVs involving FOXF1 and its upstream enhancer. Our data demonstrate that genomic imprinting at 16q24.1 plays an important role in variable ACDMPV manifestation likely through long-range regulation of FOXF1 expression, and may be also responsible for key phenotypic features of maternal uniparental disomy 16. Moreover, in one family, WES revealed a de novo missense variant in ESRP1, potentially implicating FGF signaling in the etiology of ACDMPV.
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http://dx.doi.org/10.1007/s00439-016-1655-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5518754PMC
May 2016

Exploring the genetic basis of 3MC syndrome: Findings in 12 further families.

Am J Med Genet A 2016 May 20;170A(5):1216-24. Epub 2016 Jan 20.

Manchester Centre for Genomic Medicine, Central Manchester University Hospitals NHS Foundation Trust, MAHSC, Manchester, United Kingdom.

The 3MC syndromes are a group of rare autosomal recessive disorders where the main clinical features are cleft lip and palate, hypertelorism, highly arched eyebrows, caudal appendage, postnatal growth deficiency, and genitourinary tract anomalies. Ophthalmological abnormalities, most notably anterior chamber defects may also be seen. We describe the clinical and molecular findings in 13 individuals with suspected 3MC syndrome from 12 previously unreported families. The exclusion of the MASP1 and COLEC11 Loci in two individuals from different consanguineous families and the absence of mutations in four further individuals sequenced for both genes raises the possibility that that there is further genetic heterogeneity of 3MC syndrome.
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http://dx.doi.org/10.1002/ajmg.a.37564DOI Listing
May 2016

Eight Novel Mutations Confirm the Role of AAGAB in Punctate Palmoplantar Keratoderma Type 1 (Buschke-Fischer-Brauer) and Show Broad Phenotypic Variability.

Acta Derm Venereol 2016 May;96(4):468-72

Department of Dermatology, Ludwig-Maximilian University, Munich, Germany.

Punctate palmoplantar keratoderma (PPKP1; Buschke-Fischer-Brauer) is a rare autosomal dominant inherited skin disease characterized by multiple hyperkeratotic papules involving the palms and soles. Mutations have been found at 2 loci, on chromosomes 15q22-15q24 and 8q24.13-8q24.21. We recently identified mutations in 3 families, in the AAGAB gene on 15q, which encodes the alpha- and gamma-adaptin-binding protein p34. The current study examined 14 additional families, comprising a total of 26 affected individuals and identified 8 novel mutations in 9 families. In one family a mutation that was present only in the affected individuals was found, and in 4 other families, previously reported mutations were found (1, 2). These results confirm the role of AAGAB in PPKP1. Our findings suggest that there is no correlation with age, but with mechanical factors. No additional obvious genotype-phenotype correlation was observed, even when comparing different types of mutations. Rather, identical genotypes presented a very broad interfamilial and intrafamilial variability of phenotypes.
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http://dx.doi.org/10.2340/00015555-2304DOI Listing
May 2016

The diagnostic value of next generation sequencing in familial nonsyndromic congenital heart defects.

Am J Med Genet A 2015 Aug 30;167A(8):1822-9. Epub 2015 Apr 30.

Department of Human Genetics, KU Leuven, Leuven, Belgium.

To determine the diagnostic value of massive parallel sequencing of a panel of known cardiac genes in familial nonsyndromic congenital heart defects (CHD), targeted sequencing of the coding regions of 57 genes previously implicated in CHD was performed in 36 patients from 13 nonsyndromic CHD families with probable autosomal dominant inheritance. Following variant analysis and Sanger validation, we identified six potential disease causing variants in three genes (MYH6, NOTCH1, and TBX5), which may explain the defects in six families. Several problematic situations were encountered when performing genotype-phenotype correlations in the families to confirm the causality of these variants. In conclusion, by screening known CHD-associated genes in well-selected nonsyndromic CHD families and cautious variant interpretation, potential causative variants were identified in less than half of the families (6 out of 13; 46%). Variant interpretation remains a major challenge reflecting the complex genetic cause of CHD.
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http://dx.doi.org/10.1002/ajmg.a.37108DOI Listing
August 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

Baraitser-Winter cerebrofrontofacial syndrome: delineation of the spectrum in 42 cases.

Eur J Hum Genet 2015 Mar 23;23(3):292-301. Epub 2014 Jul 23.

Institute of Medical Genetics, University Hospital of Wales, Cardiff, UK.

Baraitser-Winter, Fryns-Aftimos and cerebrofrontofacial syndrome types 1 and 3 have recently been associated with heterozygous gain-of-function mutations in one of the two ubiquitous cytoplasmic actin-encoding genes ACTB and ACTG1 that encode β- and γ-actins. We present detailed phenotypic descriptions and neuroimaging on 36 patients analyzed by our group and six cases from the literature with a molecularly proven actinopathy (9 ACTG1 and 33 ACTB). The major clinical anomalies are striking dysmorphic facial features with hypertelorism, broad nose with large tip and prominent root, congenital non-myopathic ptosis, ridged metopic suture and arched eyebrows. Iris or retinal coloboma is present in many cases, as is sensorineural deafness. Cleft lip and palate, hallux duplex, congenital heart defects and renal tract anomalies are seen in some cases. Microcephaly may develop with time. Nearly all patients with ACTG1 mutations, and around 60% of those with ACTB mutations have some degree of pachygyria with anteroposterior severity gradient, rarely lissencephaly or neuronal heterotopia. Reduction of shoulder girdle muscle bulk and progressive joint stiffness is common. Early muscular involvement, occasionally with congenital arthrogryposis, may be present. Progressive, severe dystonia was seen in one family. Intellectual disability and epilepsy are variable in severity and largely correlate with CNS anomalies. One patient developed acute lymphocytic leukemia, and another a cutaneous lymphoma, indicating that actinopathies may be cancer-predisposing disorders. Considering the multifaceted role of actins in cell physiology, we hypothesize that some clinical manifestations may be partially mutation specific. Baraitser-Winter cerebrofrontofacial syndrome is our suggested designation for this clinical entity.
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http://dx.doi.org/10.1038/ejhg.2014.95DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4326722PMC
March 2015