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1.
Am J Med Genet A ; 194(6): e63514, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38329159

ABSTRACT

Genetics has become a critical component of medicine over the past five to six decades. Alongside genetics, a relatively new discipline, dysmorphology, has also begun to play an important role in providing critically important diagnoses to individuals and families. Both have become indispensable to unraveling rare diseases. Almost every medical specialty relies on individuals experienced in these specialties to provide diagnoses for patients who present themselves to other doctors. Additionally, both specialties have become reliant on molecular geneticists to identify genes associated with human disorders. Many of the medical geneticists, dysmorphologists, and molecular geneticists traveled a circuitous route before arriving at the position they occupied. The purpose of collecting the memoirs contained in this article was to convey to the reader that many of the individuals who contributed to the advancement of genetics and dysmorphology since the late 1960s/early 1970s traveled along a journey based on many chances taken, replying to the necessities they faced along the way before finding full enjoyment in the practice of medical and human genetics or dysmorphology. Additionally, and of equal importance, all exhibited an ability to evolve with their field of expertise as human genetics became human genomics with the development of novel technologies.


Subject(s)
Genetics, Medical , Humans , History, 20th Century , History, 21st Century , Human Genetics
2.
HGG Adv ; 4(1): 100157, 2023 01 12.
Article in English | MEDLINE | ID: mdl-36408368

ABSTRACT

WDR5 is a broadly studied, highly conserved key protein involved in a wide array of biological functions. Among these functions, WDR5 is a part of several protein complexes that affect gene regulation via post-translational modification of histones. We collected data from 11 unrelated individuals with six different rare de novo germline missense variants in WDR5; one identical variant was found in five individuals and another variant in two individuals. All individuals had neurodevelopmental disorders including speech/language delays (n = 11), intellectual disability (n = 9), epilepsy (n = 7), and autism spectrum disorder (n = 4). Additional phenotypic features included abnormal growth parameters (n = 7), heart anomalies (n = 2), and hearing loss (n = 2). Three-dimensional protein structures indicate that all the residues affected by these variants are located at the surface of one side of the WDR5 protein. It is predicted that five out of the six amino acid substitutions disrupt interactions of WDR5 with RbBP5 and/or KMT2A/C, as part of the COMPASS (complex proteins associated with Set1) family complexes. Our experimental approaches in Drosophila melanogaster and human cell lines show normal protein expression, localization, and protein-protein interactions for all tested variants. These results, together with the clustering of variants in a specific region of WDR5 and the absence of truncating variants so far, suggest that dominant-negative or gain-of-function mechanisms might be at play. All in all, we define a neurodevelopmental disorder associated with missense variants in WDR5 and a broad range of features. This finding highlights the important role of genes encoding COMPASS family proteins in neurodevelopmental disorders.


Subject(s)
Autism Spectrum Disorder , Drosophila Proteins , Language Development Disorders , Neurodevelopmental Disorders , Animals , Humans , Autism Spectrum Disorder/genetics , Drosophila melanogaster/genetics , Neurodevelopmental Disorders/genetics , Cluster Analysis , Chromatin , Intracellular Signaling Peptides and Proteins/genetics , Histone-Lysine N-Methyltransferase/genetics , Drosophila Proteins/genetics
3.
Eur J Hum Genet ; 31(1): 81-88, 2023 01.
Article in English | MEDLINE | ID: mdl-36114283

ABSTRACT

Genome sequencing (GS) can identify novel diagnoses for patients who remain undiagnosed after routine diagnostic procedures. We tested whether GS is a better first-tier genetic diagnostic test than current standard of care (SOC) by assessing the technical and clinical validity of GS for patients with neurodevelopmental disorders (NDD). We performed both GS and exome sequencing in 150 consecutive NDD patient-parent trios. The primary outcome was diagnostic yield, calculated from disease-causing variants affecting exonic sequence of known NDD genes. GS (30%, n = 45) and SOC (28.7%, n = 43) had similar diagnostic yield. All 43 conclusive diagnoses obtained with SOC testing were also identified by GS. SOC, however, required integration of multiple test results to obtain these diagnoses. GS yielded two more conclusive diagnoses, and four more possible diagnoses than ES-based SOC (35 vs. 31). Interestingly, these six variants detected only by GS were copy number variants (CNVs). Our data demonstrate the technical and clinical validity of GS to serve as routine first-tier genetic test for patients with NDD. Although the additional diagnostic yield from GS is limited, GS comprehensively identified all variants in a single experiment, suggesting that GS constitutes a more efficient genetic diagnostic workflow.


Subject(s)
Neurodevelopmental Disorders , Humans , Neurodevelopmental Disorders/diagnosis , Neurodevelopmental Disorders/genetics , Genetic Testing/methods , Base Sequence , Chromosome Mapping , Exome Sequencing
4.
Transl Psychiatry ; 12(1): 421, 2022 10 01.
Article in English | MEDLINE | ID: mdl-36182950

ABSTRACT

CHD8, a major autism gene, functions in chromatin remodelling and has various roles involving several biological pathways. Therefore, unsurprisingly, previous studies have shown that intellectual developmental disorder with autism and macrocephaly (IDDAM), the syndrome caused by pathogenic variants in CHD8, consists of a broad range of phenotypic abnormalities. We collected and reviewed 106 individuals with IDDAM, including 36 individuals not previously published, thus enabling thorough genotype-phenotype analyses, involving the CHD8 mutation spectrum, characterization of the CHD8 DNA methylation episignature, and the systematic analysis of phenotypes collected in Human Phenotype Ontology (HPO). We identified 29 unique nonsense, 25 frameshift, 24 missense, and 12 splice site variants. Furthermore, two unique inframe deletions, one larger deletion (exons 26-28), and one translocation were observed. Methylation analysis was performed for 13 patients, 11 of which showed the previously established episignature for IDDAM (85%) associated with CHD8 haploinsufficiency, one analysis was inconclusive, and one showing a possible gain-of-function signature instead of the expected haploinsufficiency signature was observed. Consistent with previous studies, phenotypical abnormalities affected multiple organ systems. Many neurological abnormalities, like intellectual disability (68%) and hypotonia (29%) were observed, as well as a wide variety of behavioural abnormalities (88%). Most frequently observed behavioural problems included autism spectrum disorder (76%), short attention span (32%), abnormal social behaviour (31%), sleep disturbance (29%) and impaired social interactions (28%). Furthermore, abnormalities in the digestive (53%), musculoskeletal (79%) and genitourinary systems (18%) were noted. Although no significant difference in severity was observed between males and females, individuals with a missense variant were less severely affected. Our study provides an extensive review of all phenotypic abnormalities in patients with IDDAM and provides clinical recommendations, which will be of significant value to individuals with a pathogenic variant in CHD8, their families, and clinicians as it gives a more refined insight into the clinical and molecular spectrum of IDDAM, which is essential for accurate care and counselling.


Subject(s)
Autism Spectrum Disorder , Autistic Disorder , Intellectual Disability , Megalencephaly , Autism Spectrum Disorder/genetics , Autistic Disorder/genetics , DNA-Binding Proteins/genetics , Female , Genetic Association Studies , Humans , Intellectual Disability/genetics , Male , Megalencephaly/genetics , Phenotype , Transcription Factors/genetics
5.
Horm Res Paediatr ; 94(7-8): 285-296, 2021.
Article in English | MEDLINE | ID: mdl-34607328

ABSTRACT

INTRODUCTION: Kabuki syndrome (KS) is a genetic disorder with characteristic facial dysmorphisms, short stature, hypertension, and obesity later in life. The aim of this study was to evaluate catch-up growth and cardiovascular markers before and during growth hormone (rhGH) treatment in KS children. METHODS: This prospective study included 18 children whose KS was genetically established. Each KS subject received rhGH for a period of 2 years. Several measurements were performed before and during treatment: anthropometry, glucose metabolism, lipid profile, markers for endothelial function, and low-grade inflammation. RESULTS: This study found an increase in delta height standard deviation score (SDS) for the whole group of 1.1 SDS after 2 years of rhGH treatment. Baseline metabolic profiles showed no cardiometabolic abnormalities in these children. Although 4 out of 18 children were obese, there were no signs of the metabolic syndrome. During rhGH treatment, serum low-density lipoprotein cholesterol concentrations decreased significantly (2.16-1.91 mmol/L, p = 0.04). Apolipoprotein B100 concentrations also showed a reduction after 24 months of treatment, but the other lipid and (apo)lipoprotein parameters did not change. While other endothelial function markers were stable, only vascular cell-adhesion molecule-1 concentrations increased (1,084-1,161 pg/mL, p < 0.01) during rhGH therapy. Furthermore, BMI and waist circumference improved during treatment. There were no signs of hypertension. CONCLUSIONS: At baseline and during rhGH therapy, there were no signs of the metabolic syndrome. This is the first study demonstrating that rhGH treatment in KS children is a safe and effective therapy and that it positively influences linear height without exerting adverse effects on a wide array of cardiovascular risk markers.


Subject(s)
Abnormalities, Multiple/drug therapy , Body Height/drug effects , Face/abnormalities , Hematologic Diseases/drug therapy , Human Growth Hormone/administration & dosage , Human Growth Hormone/pharmacology , Obesity/drug therapy , Vestibular Diseases/drug therapy , Abnormalities, Multiple/genetics , Follow-Up Studies , Hematologic Diseases/genetics , Human Growth Hormone/deficiency , Humans , Metabolic Syndrome , Prospective Studies , Vestibular Diseases/genetics , Waist Circumference
6.
Sci Rep ; 10(1): 11389, 2020 07 09.
Article in English | MEDLINE | ID: mdl-32647264

ABSTRACT

Patients diagnosed with pseudohypoparathyroidism type Ia (PHP Ia) suffer from hormonal resistance and abnormal postural features, in a condition classified as Albright hereditary osteodystrophy (AHO) syndrome. This syndrome is linked to a maternally inherited mutation in the GNAS complex locus, encoding for the GTPase subunit Gsα. Here, we investigated how platelet phenotype and omics analysis can assist in the often difficult diagnosis. By coupling to the IP receptor, Gsα induces platelet inhibition via adenylyl cyclase and cAMP-dependent protein kinase A (PKA). In platelets from seven patients with suspected AHO, one of the largest cohorts examined, we studied the PKA-induced phenotypic changes. Five patients with a confirmed GNAS mutation, displayed impairments in Gsα-dependent VASP phosphorylation, aggregation, and microfluidic thrombus formation. Analysis of the platelet phosphoproteome revealed 2,516 phosphorylation sites, of which 453 were regulated by Gsα-PKA. Common changes in the patients were: (1) a joint panel of upregulated and downregulated phosphopeptides; (2) overall PKA dependency of the upregulated phosphopeptides; (3) links to key platelet function pathways. In one patient with GNAS mutation, diagnosed as non-AHO, the changes in platelet phosphoproteome were reversed. This combined approach thus revealed multiple phenotypic and molecular biomarkers to assist in the diagnosis of suspected PHP Ia.


Subject(s)
Blood Platelets/metabolism , Chromogranins/genetics , GTP-Binding Protein alpha Subunits, Gs/genetics , Iloprost/pharmacology , Pseudohypoparathyroidism/diagnosis , Biomarkers/metabolism , Blood Platelets/drug effects , Cell Adhesion Molecules/metabolism , Child , Chromogranins/metabolism , Cyclic AMP-Dependent Protein Kinases/metabolism , Drug Resistance/genetics , Epigenesis, Genetic , Female , GTP-Binding Protein alpha Subunits, Gs/metabolism , Humans , Iloprost/therapeutic use , Male , Microfilament Proteins/metabolism , Mutation , Phosphoproteins/metabolism , Phosphorylation , Platelet Aggregation/drug effects , Platelet Aggregation/genetics , Proteome/metabolism , Proteomics , Pseudohypoparathyroidism/blood , Pseudohypoparathyroidism/genetics
9.
Nat Commun ; 9(1): 4619, 2018 11 05.
Article in English | MEDLINE | ID: mdl-30397230

ABSTRACT

Chromatin remodeling is of crucial importance during brain development. Pathogenic alterations of several chromatin remodeling ATPases have been implicated in neurodevelopmental disorders. We describe an index case with a de novo missense mutation in CHD3, identified during whole genome sequencing of a cohort of children with rare speech disorders. To gain a comprehensive view of features associated with disruption of this gene, we use a genotype-driven approach, collecting and characterizing 35 individuals with de novo CHD3 mutations and overlapping phenotypes. Most mutations cluster within the ATPase/helicase domain of the encoded protein. Modeling their impact on the three-dimensional structure demonstrates disturbance of critical binding and interaction motifs. Experimental assays with six of the identified mutations show that a subset directly affects ATPase activity, and all but one yield alterations in chromatin remodeling. We implicate de novo CHD3 mutations in a syndrome characterized by intellectual disability, macrocephaly, and impaired speech and language.


Subject(s)
DNA Helicases/genetics , Developmental Disabilities/genetics , Language Disorders/genetics , Megalencephaly/genetics , Mi-2 Nucleosome Remodeling and Deacetylase Complex/genetics , Mutation, Missense , Neurodevelopmental Disorders/genetics , Protein Domains/genetics , Speech Disorders/genetics , Adenosine Triphosphatases , Child, Preschool , Chromatin Assembly and Disassembly , Female , Gene Expression , Genotype , HEK293 Cells , Humans , Intellectual Disability/genetics , Male , Models, Molecular , Phenotype , Whole Genome Sequencing
10.
Eur Thyroid J ; 7(3): 155-161, 2018 Jun.
Article in English | MEDLINE | ID: mdl-30023349

ABSTRACT

PURPOSE: To investigate thyroid gland characteristics on 18F-FDG positron emission tomography/computed tomography (PET/CT) imaging in patients with neurofibromatosis type 1 (NF1). SUBJECTS AND METHODS: Thyroid gland characteristics of patients with a clinical diagnosis of NF1 who underwent 18F-FDG PET/CT imaging for the first time to distinguish benign neurofibroma from malignant peripheral nerve sheath tumor (MPNST) at our institution (n = 69) were compared to PET/CT imaging of sarcoidosis (n = 25) and early stage lung cancer (T1N0M0 tumors, n = 15) patients. RESULTS: Two NF1 patients (3%) showed a diffuse 18F-FDG uptake in the thyroid gland, 2 patients (3%) had an irregular uptake, and 7 patients (10%) had a focal uptake. Among the sarcoidosis patients, 1 showed a diffuse uptake (4%) and 1 had an irregular uptake (4%). In the early stage lung cancer group, 1 patient showed a diffuse uptake (7%) and 1 had a focal uptake (7%). NF1 patients had larger mean thyroid volume and mean SUVmax compared to sarcoidosis patients but not compared to early stage lung cancer patients. Four NF1 patients were diagnosed with multinodular goiter, 2 patients were diagnosed with benign chronic lymphocytic thyroiditis, 1 patient had metastasis to the thyroid, and 1 patient had medullary thyroid cancer. CONCLUSION: Even though NF1 patients did not show an increased risk of thyroid incidentaloma on PET/CT compared to previous studies on non-thyroid cancer patients, the incidence shows that awareness of possible thyroid disease is important.

11.
Nat Genet ; 50(2): 175-179, 2018 02.
Article in English | MEDLINE | ID: mdl-29311637

ABSTRACT

Study of monogenic forms of obesity has demonstrated the pivotal role of the central leptin-melanocortin pathway in controlling energy balance, appetite and body weight 1 . The majority of loss-of-function mutations (mostly recessive or co-dominant) have been identified in genes that are directly involved in leptin-melanocortin signaling. These genes, however, only explain obesity in <5% of cases, predominantly from outbred populations 2 . We previously showed that, in a consanguineous population in Pakistan, recessive mutations in known obesity-related genes explain ~30% of cases with severe obesity3-5. These data suggested that new monogenic forms of obesity could also be identified in this population. Here we identify and functionally characterize homozygous mutations in the ADCY3 gene encoding adenylate cyclase 3 in children with severe obesity from consanguineous Pakistani families, as well as compound heterozygous mutations in a severely obese child of European-American descent. These findings highlight ADCY3 as an important mediator of energy homeostasis and an attractive pharmacological target in the treatment of obesity.


Subject(s)
Adenylyl Cyclases/genetics , Loss of Function Mutation , Obesity, Morbid/genetics , Adenylyl Cyclases/chemistry , Adolescent , Animals , Case-Control Studies , Cells, Cultured , Child , Cohort Studies , Consanguinity , Cricetinae , Energy Metabolism/genetics , Female , Gene Frequency , Genetic Predisposition to Disease , Homozygote , Humans , Male , Mice , Mice, Knockout , Models, Molecular , Obesity, Morbid/epidemiology , Obesity, Morbid/metabolism , Pakistan/epidemiology , Pedigree
12.
Eur J Hum Genet ; 26(1): 54-63, 2018 01.
Article in English | MEDLINE | ID: mdl-29209020

ABSTRACT

Genotype-first combined with reverse phenotyping has shown to be a powerful tool in human genetics, especially in the era of next generation sequencing. This combines the identification of individuals with mutations in the same gene and linking these to consistent (endo)phenotypes to establish disease causality. We have performed a MIP (molecular inversion probe)-based targeted re-sequencing study in 3,275 individuals with intellectual disability (ID) to facilitate a genotype-first approach for 24 genes previously implicated in ID.Combining our data with data from a publicly available database, we confirmed 11 of these 24 genes to be relevant for ID. Amongst these, PHIP was shown to have an enrichment of disruptive mutations in the individuals with ID (5 out of 3,275). Through international collaboration, we identified a total of 23 individuals with PHIP mutations and elucidated the associated phenotype. Remarkably, all 23 individuals had developmental delay/ID and the majority were overweight or obese. Other features comprised behavioral problems (hyperactivity, aggression, features of autism and/or mood disorder) and dysmorphisms (full eyebrows and/or synophrys, upturned nose, large ears and tapering fingers). Interestingly, PHIP encodes two protein-isoforms, PHIP/DCAF14 and NDRP, each involved in neurodevelopmental processes, including E3 ubiquitination and neuronal differentiation. Detailed genotype-phenotype analysis points towards haploinsufficiency of PHIP/DCAF14, and not NDRP, as the underlying cause of the phenotype.Thus, we demonstrated the use of large scale re-sequencing by MIPs, followed by reverse phenotyping, as a constructive approach to verify candidate disease genes and identify novel syndromes, highlighted by PHIP haploinsufficiency causing an ID-overweight syndrome.


Subject(s)
Genetic Testing/methods , Genotype , Intellectual Disability/genetics , Intracellular Signaling Peptides and Proteins/genetics , Overweight/genetics , Adolescent , Adult , Child , Female , Genetic Testing/standards , Haploinsufficiency , Humans , Male , Reproducibility of Results , Sequence Analysis, DNA/methods , Sequence Analysis, DNA/standards , Syndrome
13.
J Med Genet ; 55(2): 104-113, 2018 02.
Article in English | MEDLINE | ID: mdl-29097605

ABSTRACT

BACKGROUND: De novo mutations in PURA have recently been described to cause PURA syndrome, a neurodevelopmental disorder characterised by severe intellectual disability (ID), epilepsy, feeding difficulties and neonatal hypotonia. OBJECTIVES: To delineate the clinical spectrum of PURA syndrome and study genotype-phenotype correlations. METHODS: Diagnostic or research-based exome or Sanger sequencing was performed in individuals with ID. We systematically collected clinical and mutation data on newly ascertained PURA syndrome individuals, evaluated data of previously reported individuals and performed a computational analysis of photographs. We classified mutations based on predicted effect using 3D in silico models of crystal structures of Drosophila-derived Pur-alpha homologues. Finally, we explored genotype-phenotype correlations by analysis of both recurrent mutations as well as mutation classes. RESULTS: We report mutations in PURA (purine-rich element binding protein A) in 32 individuals, the largest cohort described so far. Evaluation of clinical data, including 22 previously published cases, revealed that all have moderate to severe ID and neonatal-onset symptoms, including hypotonia (96%), respiratory problems (57%), feeding difficulties (77%), exaggerated startle response (44%), hypersomnolence (66%) and hypothermia (35%). Epilepsy (54%) and gastrointestinal (69%), ophthalmological (51%) and endocrine problems (42%) were observed frequently. Computational analysis of facial photographs showed subtle facial dysmorphism. No strong genotype-phenotype correlation was identified by subgrouping mutations into functional classes. CONCLUSION: We delineate the clinical spectrum of PURA syndrome with the identification of 32 additional individuals. The identification of one individual through targeted Sanger sequencing points towards the clinical recognisability of the syndrome. Genotype-phenotype analysis showed no significant correlation between mutation classes and disease severity.


Subject(s)
DNA-Binding Proteins/genetics , Face/abnormalities , Intellectual Disability/genetics , Mutation , Transcription Factors/genetics , DNA-Binding Proteins/chemistry , Drosophila Proteins/chemistry , Drosophila Proteins/genetics , Eye Abnormalities/genetics , Female , Genetic Association Studies , Humans , Infant, Newborn , Muscle Hypotonia/etiology , Muscle Hypotonia/genetics , Pregnancy , Structural Homology, Protein , Syndrome , Transcription Factors/chemistry
14.
PLoS Genet ; 13(10): e1006864, 2017 Oct.
Article in English | MEDLINE | ID: mdl-29069077

ABSTRACT

Kleefstra syndrome, caused by haploinsufficiency of euchromatin histone methyltransferase 1 (EHMT1), is characterized by intellectual disability (ID), autism spectrum disorder (ASD), characteristic facial dysmorphisms, and other variable clinical features. In addition to EHMT1 mutations, de novo variants were reported in four additional genes (MBD5, SMARCB1, NR1I3, and KMT2C), in single individuals with clinical characteristics overlapping Kleefstra syndrome. Here, we present a novel cohort of five patients with de novo loss of function mutations affecting the histone methyltransferase KMT2C. Our clinical data delineates the KMT2C phenotypic spectrum and reinforces the phenotypic overlap with Kleefstra syndrome and other related ID disorders. To elucidate the common molecular basis of the neuropathology associated with mutations in KMT2C and EHMT1, we characterized the role of the Drosophila KMT2C ortholog, trithorax related (trr), in the nervous system. Similar to the Drosophila EHMT1 ortholog, G9a, trr is required in the mushroom body for short term memory. Trr ChIP-seq identified 3371 binding sites, mainly in the promoter of genes involved in neuronal processes. Transcriptional profiling of pan-neuronal trr knockdown and G9a null mutant fly heads identified 613 and 1123 misregulated genes, respectively. These gene sets show a significant overlap and are associated with nearly identical gene ontology enrichments. The majority of the observed biological convergence is derived from predicted indirect target genes. However, trr and G9a also have common direct targets, including the Drosophila ortholog of Arc (Arc1), a key regulator of synaptic plasticity. Our data highlight the clinical and molecular convergence between the KMT2 and EHMT protein families, which may contribute to a molecular network underlying a larger group of ID/ASD-related disorders.


Subject(s)
Autism Spectrum Disorder/genetics , Craniofacial Abnormalities/genetics , Cytoskeletal Proteins/genetics , DNA-Binding Proteins/genetics , Drosophila Proteins/genetics , Heart Defects, Congenital/genetics , Histone-Lysine N-Methyltransferase/genetics , Intellectual Disability/genetics , Nerve Tissue Proteins/genetics , Adolescent , Adult , Animals , Autism Spectrum Disorder/physiopathology , Binding Sites/genetics , Child , Chromosome Deletion , Chromosomes, Human, Pair 9/genetics , Constitutive Androstane Receptor , Craniofacial Abnormalities/physiopathology , Drosophila melanogaster/genetics , Female , Gene Expression Regulation , Haploinsufficiency , Heart Defects, Congenital/physiopathology , Histones/genetics , Humans , Intellectual Disability/physiopathology , Male , Mutation , Neuronal Plasticity/genetics , Promoter Regions, Genetic
15.
Am J Med Genet A ; 173(3): 771-775, 2017 Mar.
Article in English | MEDLINE | ID: mdl-28211972

ABSTRACT

Tuberous sclerosis complex (TSC) is an autosomal dominantly inherited disorder with variable expressivity associated with hamartomatous tumors, abnormalities of the skin, and neurologic problems including seizures, intellectual disability, and autism. TSC is caused by pathogenic variants in either TSC1 or TSC2. In general, TSC2 pathogenic variants are associated with a more severe phenotype than TSC1 pathogenic variants. Here, we report a pathogenic TSC2 variant, c.1864C>T, p.(Arg622Trp), associated with a mild phenotype, with most carriers meeting fewer than two major clinical diagnostic criteria for TSC. This finding has significant implications for counseling patients regarding prognosis. More patient data are required before changing the surveillance recommendations for patients with the reported variant. However, consideration should be given to tailoring surveillance recommendations for all pathogenic TSC1 and TSC2 variants with documented milder clinical sequelae. © 2017 Wiley Periodicals, Inc.


Subject(s)
Alleles , Genetic Association Studies , Mutation , Phenotype , Tuberous Sclerosis/diagnosis , Tuberous Sclerosis/genetics , Tumor Suppressor Proteins/genetics , Amino Acid Substitution , Brain/pathology , Child , Child, Preschool , Female , Genotype , Humans , Infant, Newborn , Magnetic Resonance Imaging , Male , Pedigree , Rhabdomyoma/diagnosis , Rhabdomyoma/genetics , Rhabdomyoma/surgery , Severity of Illness Index , Tuberous Sclerosis Complex 2 Protein
16.
Genet Med ; 19(1): 45-52, 2017 01.
Article in English | MEDLINE | ID: mdl-27195816

ABSTRACT

PURPOSE: Truncating mutations in the maternally imprinted, paternally expressed gene MAGEL2, which is located in the Prader-Willi critical region 15q11-13, have recently been reported to cause Schaaf-Yang syndrome, a Prader-Willi-like disease that manifests as developmental delay/intellectual disability, hypotonia, feeding difficulties, and autism spectrum disorder. The causality of the reported variants in the context of the patients' phenotypes was questioned, as MAGEL2 whole-gene deletions seem to cause little or no clinical phenotype. METHODS: Here we report a total of 18 newly identified individuals with Schaaf-Yang syndrome from 14 families, including 1 family with 3 individuals found to be affected with a truncating variant of MAGEL2, 11 individuals who are clinically affected but were not tested molecularly, and a presymptomatic fetal sibling carrying the pathogenic MAGEL2 variant. RESULTS: All cases harbor truncating mutations of MAGEL2, and nucleotides c.1990-1996 arise as a mutational hotspot, with 10 individuals and 1 fetus harboring a c.1996dupC (p.Q666fs) mutation and 2 fetuses harboring a c.1996delC (p.Q666fs) mutation. The phenotypic spectrum of Schaaf-Yang syndrome ranges from fetal akinesia to neurobehavioral disease and contractures of the small finger joints. CONCLUSION: This study provides strong evidence for the pathogenicity of truncating mutations of the paternal allele of MAGEL2, refines the associated clinical phenotypes, and highlights implications for genetic counseling for affected families.Genet Med 19 1, 45-52.


Subject(s)
Autism Spectrum Disorder/genetics , Developmental Disabilities/genetics , Intellectual Disability/genetics , Prader-Willi Syndrome/genetics , Proteins/genetics , Adolescent , Adult , Autism Spectrum Disorder/physiopathology , Child , Child, Preschool , Chromosomes, Human, Pair 15 , Developmental Disabilities/physiopathology , Female , Gene Expression , Genomic Imprinting , Humans , Infant , Infant, Newborn , Intellectual Disability/physiopathology , Male , Mutation , Phenotype , Prader-Willi Syndrome/physiopathology
17.
Am J Hum Genet ; 99(3): 711-719, 2016 09 01.
Article in English | MEDLINE | ID: mdl-27545680

ABSTRACT

The overall understanding of the molecular etiologies of intellectual disability (ID) and developmental delay (DD) is increasing as next-generation sequencing technologies identify genetic variants in individuals with such disorders. However, detailed analyses conclusively confirming these variants, as well as the underlying molecular mechanisms explaining the diseases, are often lacking. Here, we report on an ID syndrome caused by de novo heterozygous loss-of-function (LoF) mutations in SON. The syndrome is characterized by ID and/or DD, malformations of the cerebral cortex, epilepsy, vision problems, musculoskeletal abnormalities, and congenital malformations. Knockdown of son in zebrafish resulted in severe malformation of the spine, brain, and eyes. Importantly, analyses of RNA from affected individuals revealed that genes critical for neuronal migration and cortex organization (TUBG1, FLNA, PNKP, WDR62, PSMD3, and HDAC6) and metabolism (PCK2, PFKL, IDH2, ACY1, and ADA) are significantly downregulated because of the accumulation of mis-spliced transcripts resulting from erroneous SON-mediated RNA splicing. Our data highlight SON as a master regulator governing neurodevelopment and demonstrate the importance of SON-mediated RNA splicing in human development.


Subject(s)
Brain/embryology , Brain/metabolism , DNA-Binding Proteins/genetics , Genes, Essential/genetics , Intellectual Disability/genetics , Minor Histocompatibility Antigens/genetics , Mutation/genetics , RNA Splicing/genetics , Animals , Brain/abnormalities , Brain/pathology , DNA-Binding Proteins/analysis , DNA-Binding Proteins/metabolism , Developmental Disabilities/genetics , Developmental Disabilities/pathology , Developmental Disabilities/physiopathology , Eye Abnormalities/genetics , Female , Haploinsufficiency/genetics , Head/abnormalities , Heterozygote , Humans , Intellectual Disability/pathology , Intellectual Disability/physiopathology , Male , Metabolic Diseases/genetics , Metabolic Diseases/metabolism , Minor Histocompatibility Antigens/analysis , Minor Histocompatibility Antigens/metabolism , Pedigree , RNA, Messenger/analysis , Spine/abnormalities , Syndrome , Zebrafish/abnormalities , Zebrafish/embryology , Zebrafish/genetics
18.
Am J Hum Genet ; 98(3): 541-552, 2016 Mar 03.
Article in English | MEDLINE | ID: mdl-26942287

ABSTRACT

Intellectual disability (ID) and autism spectrum disorders (ASD) are genetically heterogeneous, and a significant number of genes have been associated with both conditions. A few mutations in POGZ have been reported in recent exome studies; however, these studies do not provide detailed clinical information. We collected the clinical and molecular data of 25 individuals with disruptive mutations in POGZ by diagnostic whole-exome, whole-genome, or targeted sequencing of 5,223 individuals with neurodevelopmental disorders (ID primarily) or by targeted resequencing of this locus in 12,041 individuals with ASD and/or ID. The rarity of disruptive mutations among unaffected individuals (2/49,401) highlights the significance (p = 4.19 × 10(-13); odds ratio = 35.8) and penetrance (65.9%) of this genetic subtype with respect to ASD and ID. By studying the entire cohort, we defined common phenotypic features of POGZ individuals, including variable levels of developmental delay (DD) and more severe speech and language delay in comparison to the severity of motor delay and coordination issues. We also identified significant associations with vision problems, microcephaly, hyperactivity, a tendency to obesity, and feeding difficulties. Some features might be explained by the high expression of POGZ, particularly in the cerebellum and pituitary, early in fetal brain development. We conducted parallel studies in Drosophila by inducing conditional knockdown of the POGZ ortholog row, further confirming that dosage of POGZ, specifically in neurons, is essential for normal learning in a habituation paradigm. Combined, the data underscore the pathogenicity of loss-of-function mutations in POGZ and define a POGZ-related phenotype enriched in specific features.


Subject(s)
Autism Spectrum Disorder/genetics , Intellectual Disability/genetics , Transposases/genetics , Adolescent , Adult , Animals , Autism Spectrum Disorder/diagnosis , Child , Child, Preschool , Cohort Studies , Down-Regulation , Drosophila/genetics , Drosophila Proteins/genetics , Drosophila Proteins/metabolism , Exome , Female , Gene Knockdown Techniques , Genome-Wide Association Study , Humans , Infant , Intellectual Disability/diagnosis , Language Development Disorders/diagnosis , Language Development Disorders/genetics , Linear Models , Male , Microcephaly/diagnosis , Microcephaly/genetics , Mutation , Phenotype , Transcription Factors/genetics , Transcription Factors/metabolism
19.
Am J Hum Genet ; 97(2): 343-52, 2015 Aug 06.
Article in English | MEDLINE | ID: mdl-26235985

ABSTRACT

Intellectual disability (ID) affects approximately 1%-3% of humans with a gender bias toward males. Previous studies have identified mutations in more than 100 genes on the X chromosome in males with ID, but there is less evidence for de novo mutations on the X chromosome causing ID in females. In this study we present 35 unique deleterious de novo mutations in DDX3X identified by whole exome sequencing in 38 females with ID and various other features including hypotonia, movement disorders, behavior problems, corpus callosum hypoplasia, and epilepsy. Based on our findings, mutations in DDX3X are one of the more common causes of ID, accounting for 1%-3% of unexplained ID in females. Although no de novo DDX3X mutations were identified in males, we present three families with segregating missense mutations in DDX3X, suggestive of an X-linked recessive inheritance pattern. In these families, all males with the DDX3X variant had ID, whereas carrier females were unaffected. To explore the pathogenic mechanisms accounting for the differences in disease transmission and phenotype between affected females and affected males with DDX3X missense variants, we used canonical Wnt defects in zebrafish as a surrogate measure of DDX3X function in vivo. We demonstrate a consistent loss-of-function effect of all tested de novo mutations on the Wnt pathway, and we further show a differential effect by gender. The differential activity possibly reflects a dose-dependent effect of DDX3X expression in the context of functional mosaic females versus one-copy males, which reflects the complex biological nature of DDX3X mutations.


Subject(s)
DEAD-box RNA Helicases/genetics , Intellectual Disability/genetics , Mutation, Missense/genetics , Phenotype , Sex Characteristics , Wnt Signaling Pathway/genetics , Amino Acid Substitution/genetics , Animals , Base Sequence , Embryo, Nonmammalian/metabolism , Embryo, Nonmammalian/pathology , Exome/genetics , Female , Gene Dosage/genetics , Humans , Intellectual Disability/pathology , Male , Molecular Sequence Data , Sequence Analysis, DNA , Zebrafish
20.
PLoS One ; 10(4): e0122648, 2015.
Article in English | MEDLINE | ID: mdl-25837634

ABSTRACT

General practitioners (GPs) are increasingly called upon to identify patients at risk for hereditary cancers, and their genetic competencies need to be enhanced. This article gives an overview of a research project on how to build effective educational modules on genetics, assessed by randomized controlled trials (RCTs), reflecting the prioritized educational needs of primary care physicians. It also reports on an ongoing study to investigate long-term increase in genetic consultation skills (1-year follow-up) and interest in and satisfaction with a supportive website on genetics among GPs. Three oncogenetics modules were developed: an online Continuing Professional Development (G-eCPD) module, a live genetic CPD module, and a "GP and genetics" website (huisartsengenetica.nl) providing further genetics information applicable in daily practice. Three assessments to evaluate the effectiveness (1-year follow-up) of the oncogenetic modules were designed: 1.An online questionnaire on self-reported genetic competencies and changes in referral behaviour, 2.Referral rates from GPs to clinical genetics centres and 3.Satisfaction questionnaire and visitor count analytics of supportive genetics website. The setting was Primary care in the Netherlands and three groups of study participants were included in the reported studies:. Assessment 1. 168 GPs responded to an email invitation and were randomly assigned to an intervention or control group, evaluating the G-eCPD module (n = 80) or the live module (n = 88). Assessment 2. Referral rates by GPs were requested from the clinical genetics centres, in the northern and southern parts of the Netherlands (Amsterdam and Maastricht), for the two years before (2010 [n = 2510] and 2011 [n = 2940]) and the year after (2012 [n = 2875]) launch of the oncogenetics CPD modules and the website. Assessment 3. Participants of the website evaluation were all recruited online. When they visited the website during the month of February 2013, a pop-up invitation came up. Of the 1350 unique visitors that month, only 38 completed the online questionnaire. Main outcomes measure showed long-term (self-reported) genetic consultation skills (i.e. increased genetics awareness and referrals to clinical genetics centres) among GPs who participated in the oncogenetic training course, and interest in and satisfaction with the supportive website. 42 GPs (52%) who previously participated in the G-eCPD evaluation study and 50 GPs (57%) who participated in the live training programme responded to the online questionnaire on long-term effects of educational outcome. Previous RCTs showed that the genetics CPD modules achieved sustained improvement of oncogenetic knowledge and consultation skills (3-months follow-up). Participants of these RCTs reported being more aware of genetic problems long term; this was reported by 29 GPs (69%) and 46 GPs (92%) participating in the G-eCPD and live module evaluation studies, respectively (Chisquare test, p<0.005). One year later, 68% of the respondents attending the live training reported that they more frequently referred patients to the clinical genetics centres, compared to 29% of those who attended the online oncogenetics training (Chisquare test, p<0.0005). However, the clinical genetics centres reported no significant change in referral numbers one year after the training. Website visitor numbers increased, as did satisfaction, reflected in a 7.7 and 8.1 (out of 10) global rating of the website (by G-eCPD and live module participants, respectively). The page most often consulted was "family tree drawing". Self-perceived genetic consultation skills increased long-term and GPs were interested in and satisfied with the supportive website. Further studies are necessary to see whether the oncogenetics CPD modules result in more efficient referral. The results presented suggest we have provided a flexible and effective framework to meet the need for effective educational programmes for non-geneticist healthcare providers, enabling improvement of genetic medical care.


Subject(s)
Education, Medical, Continuing/methods , General Practitioners/education , Genetics, Medical/education , Medical Oncology/education , Consumer Behavior , Humans , Internet , Netherlands , Randomized Controlled Trials as Topic , Referral and Consultation/statistics & numerical data , Surveys and Questionnaires
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