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1.
Nat Immunol ; 17(5): 495-504, 2016 May.
Article in English | MEDLINE | ID: mdl-27019227

ABSTRACT

Aberrant nucleic acids generated during viral replication are the main trigger for antiviral immunity, and mutations that disrupt nucleic acid metabolism can lead to autoinflammatory disorders. Here we investigated the etiology of X-linked reticulate pigmentary disorder (XLPDR), a primary immunodeficiency with autoinflammatory features. We discovered that XLPDR is caused by an intronic mutation that disrupts the expression of POLA1, which encodes the catalytic subunit of DNA polymerase-α. Unexpectedly, POLA1 deficiency resulted in increased production of type I interferons. This enzyme is necessary for the synthesis of RNA:DNA primers during DNA replication and, strikingly, we found that POLA1 is also required for the synthesis of cytosolic RNA:DNA, which directly modulates interferon activation. Together this work identifies POLA1 as a critical regulator of the type I interferon response.


Subject(s)
DNA Polymerase I/metabolism , DNA/biosynthesis , Interferon Type I/metabolism , RNA/biosynthesis , Base Sequence , Cells, Cultured , Cytosol/metabolism , DNA/genetics , DNA Polymerase I/genetics , Family Health , Female , Fibroblasts/cytology , Fibroblasts/metabolism , Gene Expression Profiling , Genetic Diseases, X-Linked/genetics , Genetic Diseases, X-Linked/metabolism , HEK293 Cells , HeLa Cells , Humans , Immunoblotting , Male , Microscopy, Confocal , Mutation , Oligonucleotide Array Sequence Analysis , Pedigree , Pigmentation Disorders/genetics , Pigmentation Disorders/metabolism , RNA/genetics , Reverse Transcriptase Polymerase Chain Reaction
2.
Kidney Int ; 105(4): 844-864, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38154558

ABSTRACT

Congenital anomalies of the kidney and urinary tract (CAKUT) are the predominant cause for chronic kidney disease below age 30 years. Many monogenic forms have been discovered due to comprehensive genetic testing like exome sequencing. However, disease-causing variants in known disease-associated genes only explain a proportion of cases. Here, we aim to unravel underlying molecular mechanisms of syndromic CAKUT in three unrelated multiplex families with presumed autosomal recessive inheritance. Exome sequencing in the index individuals revealed three different rare homozygous variants in FOXD2, encoding a transcription factor not previously implicated in CAKUT in humans: a frameshift in the Arabic and a missense variant each in the Turkish and the Israeli family with segregation patterns consistent with autosomal recessive inheritance. CRISPR/Cas9-derived Foxd2 knockout mice presented with a bilateral dilated kidney pelvis accompanied by atrophy of the kidney papilla and mandibular, ophthalmologic, and behavioral anomalies, recapitulating the human phenotype. In a complementary approach to study pathomechanisms of FOXD2-dysfunction-mediated developmental kidney defects, we generated CRISPR/Cas9-mediated knockout of Foxd2 in ureteric bud-induced mouse metanephric mesenchyme cells. Transcriptomic analyses revealed enrichment of numerous differentially expressed genes important for kidney/urogenital development, including Pax2 and Wnt4 as well as gene expression changes indicating a shift toward a stromal cell identity. Histology of Foxd2 knockout mouse kidneys confirmed increased fibrosis. Further, genome-wide association studies suggest that FOXD2 could play a role for maintenance of podocyte integrity during adulthood. Thus, our studies help in genetic diagnostics of monogenic CAKUT and in understanding of monogenic and multifactorial kidney diseases.


Subject(s)
Embryonic Structures , Forkhead Transcription Factors , Kidney Diseases , Kidney , Nephrons , Urinary Tract , Urogenital Abnormalities , Vesico-Ureteral Reflux , Adult , Animals , Humans , Mice , Genome-Wide Association Study , Kidney/abnormalities , Kidney/embryology , Kidney Diseases/genetics , Mice, Knockout , Nephrons/embryology , Transcription Factors/genetics , Urogenital Abnormalities/genetics , Vesico-Ureteral Reflux/genetics , Forkhead Transcription Factors/deficiency , Forkhead Transcription Factors/metabolism
3.
Br J Haematol ; 204(3): 1067-1071, 2024 03.
Article in English | MEDLINE | ID: mdl-37984840

ABSTRACT

Biallelic pathogenic variants in CAD, that encode the multienzymatic protein required for de-novo pyrimidine biosynthesis, cause early infantile epileptic encephalopathy-50. This rare disease, characterized by developmental delay, intractable seizures and anaemia, is amenable to treatment with uridine. We present a patient with macrocytic anaemia, elevated haemoglobin-A2 levels, anisocytosis, poikilocytosis and target cells in the blood smear, and mild developmental delay. A next-generation sequencing panel revealed biallelic variants in CAD. Functional studies did not support complete abrogation of protein function; however, the patient responded to uridine supplement. We conclude that biallelic hypomorphic CAD variants may cause a primarily haematological phenotype.


Subject(s)
Anemia, Macrocytic , Anemia , Spasms, Infantile , Humans , Spasms, Infantile/genetics , Uridine , Hemoglobins
4.
Pediatr Res ; 2024 May 11.
Article in English | MEDLINE | ID: mdl-38734812

ABSTRACT

BACKGROUND: Biological similarities between inflammatory bowel disease (IBD) and familial Mediterranean fever (FMF) have been described in humans and animal models suggesting a possible common genetic basis. FMF is caused by variants in the MEFV gene which encodes pyrin, an immune regulator. This study aimed to investigate the carrier rate of disease-causing MEFV variants in children of different ethnicities diagnosed with very-early-onset IBD (VEO-IBD). METHODS: The study included 23 children diagnosed with VEO-IBD who had undergone whole exome sequencing. The exomes were evaluated for MEFV monoallelic and biallelic disease-causing variants and compared to exome sequencing data of 250 probands with suspected monogenic diseases other than IBD. RESULTS: Of the 23 children diagnosed with VEO-IBD, 12 (52%) were carriers of at least one MEFV disease-causing variant, which was threefold higher than in individuals without IBD. The most frequent variants identified were p.M694V and p.E148Q (42% each). The allelic frequency of MEFV variants was found to be higher across the VEO-IBD group in 13 of 14 ethnicities compared to the control group. CONCLUSION: The study suggests that disease-causing variants in the MEFV gene should be sought in cases of VEO-IBD. However, the clinical importance of this finding is yet to be defined. IMPACT: There are biological similarities between inflammatory bowel disease and familial Mediterranean fever, suggesting a possible genetic relationship. Children less than 6 years old clinically diagnosed with inflammatory bowel disease have a threefold higher rate of disease-causing variants in the MEFV gene than controls. Monogenic testing in children with very-early-onset inflammatory bowel disease should include a search for MEFV variants.

5.
Prenat Diagn ; 2024 Sep 05.
Article in English | MEDLINE | ID: mdl-39237446

ABSTRACT

OBJECTIVE: To investigate how many novel pathogenic (P) and likely pathogenic (LP) nonprotein-truncating or noncanonical splicing variants would be classified as variants of unknown significance (VUS) if they were detected in fetuses without abnormalities. METHODS: The study included 156 patients with neurodevelopmental disorders diagnosed through postnatal exome sequencing. Causative P/LP nonprotein-truncating and noncanonical splicing variants were retrospectively reclassified in cases without specific prenatal manifestations, disregarding postnatal symptoms. RESULTS: Of the 156 patients, 72 had a nontruncating or noncanonical splicing variant. Six patients were excluded for having more than one possible causative variant. Twelve patients had prenatal malformations known to be associated with the diagnosed disorder; therefore, variant interpretation remained unchanged. In 33 of the 54 remaining cases, the variant had been previously reported as P/LP. Reclassification of the other 21 LP/P variants revealed that 16 would have been classified as VUS if detected prenatally. CONCLUSION: In our cohort, ∼24% (16/66) of causative nonprotein-truncating/noncanonical splicing variants would have been classified as VUS if sequencing had been conducted during pregnancy. The potential for false-negative results, stemming from limitations in the phenotypic information available prenatally, should be discussed with prospective parents. The criteria for classifying and reporting variants in the prenatal setting may require adjustment.

6.
Genet Med ; 25(4): 100003, 2023 04.
Article in English | MEDLINE | ID: mdl-36549593

ABSTRACT

PURPOSE: Transformer2 proteins (Tra2α and Tra2ß) control splicing patterns in human cells, and no human phenotypes have been associated with germline variants in these genes. The aim of this work was to associate germline variants in the TRA2B gene to a novel neurodevelopmental disorder. METHODS: A total of 12 individuals from 11 unrelated families who harbored predicted loss-of-function monoallelic variants, mostly de novo, were recruited. RNA sequencing and western blot analyses of Tra2ß-1 and Tra2ß-3 isoforms from patient-derived cells were performed. Tra2ß1-GFP, Tra2ß3-GFP and CHEK1 exon 3 plasmids were transfected into HEK-293 cells. RESULTS: All variants clustered in the 5' part of TRA2B, upstream of an alternative translation start site responsible for the expression of the noncanonical Tra2ß-3 isoform. All affected individuals presented intellectual disability and/or developmental delay, frequently associated with infantile spasms, microcephaly, brain anomalies, autism spectrum disorder, feeding difficulties, and short stature. Experimental studies showed that these variants decreased the expression of the canonical Tra2ß-1 isoform, whereas they increased the expression of the Tra2ß-3 isoform, which is shorter and lacks the N-terminal RS1 domain. Increased expression of Tra2ß-3-GFP were shown to interfere with the incorporation of CHEK1 exon 3 into its mature transcript, normally incorporated by Tra2ß-1. CONCLUSION: Predicted loss-of-function variants clustered in the 5' portion of TRA2B cause a new neurodevelopmental syndrome through an apparently dominant negative disease mechanism involving the use of an alternative translation start site and the overexpression of a shorter, repressive Tra2ß protein.


Subject(s)
Autism Spectrum Disorder , Intellectual Disability , Neurodevelopmental Disorders , Humans , Alternative Splicing , RNA-Binding Proteins/genetics , HEK293 Cells , Protein Isoforms/genetics , Intellectual Disability/genetics , Neurodevelopmental Disorders/genetics , Serine-Arginine Splicing Factors/genetics , Serine-Arginine Splicing Factors/metabolism , Nerve Tissue Proteins/genetics , Nerve Tissue Proteins/metabolism
7.
Genet Med ; 25(1): 135-142, 2023 01.
Article in English | MEDLINE | ID: mdl-36399134

ABSTRACT

PURPOSE: Protein arginine methyltransferase 7 (PRMT7) is a member of a family of enzymes that catalyzes the methylation of arginine residues on several protein substrates. Biallelic pathogenic PRMT7 variants have previously been associated with a syndromic neurodevelopmental disorder characterized by short stature, brachydactyly, intellectual developmental disability, and seizures. To our knowledge, no comprehensive study describes the detailed clinical characteristics of this syndrome. Thus, we aim to delineate the phenotypic spectrum of PRMT7-related disorder. METHODS: We assembled a cohort of 51 affected individuals from 39 different families, gathering clinical information from 36 newly described affected individuals and reviewing data of 15 individuals from the literature. RESULTS: The main clinical characteristics of the PRMT7-related syndrome are short stature, mild to severe developmental delay/intellectual disability, hypotonia, brachydactyly, and distinct facial morphology, including bifrontal narrowing, prominent supraorbital ridges, sparse eyebrows, short nose with full/broad nasal tip, thin upper lip, full and everted lower lip, and a prominent or squared-off jaw. Additional variable findings include seizures, obesity, nonspecific magnetic resonance imaging abnormalities, eye abnormalities (i.e., strabismus or nystagmus), and hearing loss. CONCLUSION: This study further delineates and expands the molecular, phenotypic spectrum and natural history of PRMT7-related syndrome characterized by a neurodevelopmental disorder with skeletal, growth, and endocrine abnormalities.


Subject(s)
Brachydactyly , Dwarfism , Intellectual Disability , Musculoskeletal Abnormalities , Neurodevelopmental Disorders , Humans , Neurodevelopmental Disorders/genetics , Intellectual Disability/genetics , Dwarfism/genetics , Obesity/genetics , Phenotype , Protein-Arginine N-Methyltransferases/genetics
8.
Clin Genet ; 101(5-6): 517-529, 2022 05.
Article in English | MEDLINE | ID: mdl-35315053

ABSTRACT

Preconception carrier screening allows identification of couples at risk to have offspring with autosomal recessive and X-linked disorders. In a current multiethnic world, screening based on self-reported ancestry has limitations. Here we describe the findings of a comprehensive pan-ethnic variant-based carrier screening, using the Israeli Jewish population as a model. The cohort included 1696 individuals (848 couples) tested with the 'MyScreen' multigene panel. The panel covers 1206 variants spanning 385 genes, known in different Jewish ethnicities and local Arab, Druze and Bedouin populations. Out of these, 205 variants in 143 genes are Jewish founder variants. We identified 859 (50.6%), carriers of at least one variant in 151 genes. Importantly, 569 (66.2%) of carriers could be missed by the current Israeli screening program. In total, 1:40 (2.5%) of carrier couples were identified by the 'MyScreen' panel, compared with 1:144 (0.7%) found by the ethnicity-based screening. Surprisingly, 90 individuals (10.5%) were carriers of variants "unexpected" for their reported origin, and 16 variants were previously unreported in Jewish patients. Our results support the advantages of variant-based comprehensive carrier screening for detection of carriers and at-risk couples in a diverse population with many founder disease-causing variants.


Subject(s)
Genetic Testing , Jews , Ethnicity , Genetic Carrier Screening/methods , Humans , Israel/epidemiology , Jews/genetics
10.
Ann Neurol ; 90(5): 738-750, 2021 11.
Article in English | MEDLINE | ID: mdl-34564892

ABSTRACT

OBJECTIVE: Hereditary spastic paraplegia (HSP) is a highly heterogeneous neurologic disorder characterized by lower-extremity spasticity. Here, we set out to determine the genetic basis of an autosomal dominant, pure, and infantile-onset form of HSP in a cohort of 8 patients with a uniform clinical presentation. METHODS: Trio whole-exome sequencing was used in 5 index patients with infantile-onset pure HSP to determine the genetic cause of disease. The functional impact of identified genetic variants was verified using bioinformatics and complementary cellular and biochemical assays. RESULTS: Distinct heterozygous KPNA3 missense variants were found to segregate with the clinical phenotype in 8 patients; in 4 of them KPNA3 variants had occurred de novo. Mutant karyopherin-α3 proteins exhibited a variable pattern of altered expression level, subcellular distribution, and protein interaction. INTERPRETATION: Our genetic findings implicate heterozygous variants in KPNA3 as a novel cause for autosomal dominant, early-onset, and pure HSP. Mutant karyopherin-α3 proteins display varying deficits in molecular and cellular functions, thus, for the first time, implicating dysfunctional nucleocytoplasmic shuttling as a novel pathomechanism causing HSP. ANN NEUROL 2021;90:738-750.


Subject(s)
Mutation/genetics , Spastic Paraplegia, Hereditary/genetics , alpha Karyopherins/genetics , Adult , Child, Preschool , Heterozygote , Humans , Male , Middle Aged , Pedigree , Phenotype , Exome Sequencing/methods , Young Adult
11.
Eur J Neurol ; 29(4): 1174-1180, 2022 04.
Article in English | MEDLINE | ID: mdl-34935254

ABSTRACT

BACKGROUND AND PURPOSE: Muscular A-type lamin-interacting protein (MLIP) is most abundantly expressed in cardiac and skeletal muscle. In vitro and animal studies have shown its regulatory role in myoblast differentiation and in organization of myonuclear positioning in skeletal muscle, as well as in cardiomyocyte adaptation and cardiomyopathy. We report the association of biallelic truncating variation in the MLIP gene with human disease in five individuals from two unrelated pedigrees. METHODS: Clinical evaluation and exome sequencing were performed in two unrelated families with elevated creatine kinase level. RESULTS: Family 1. A 6-year-old girl born to consanguineous parents of Arab-Muslim origin presented with myalgia, early fatigue after mild-to-moderate physical exertion, and elevated creatine kinase levels up to 16,000 U/L. Exome sequencing revealed a novel homozygous nonsense variant, c.2530C>T; p.Arg844Ter, in the MLIP gene. Family 2. Three individuals from two distantly related families of Old Order Amish ancestry presented with elevated creatine kinase levels, one of whom also presented with abnormal electrocardiography results. On exome sequencing, all showed homozygosity for a novel nonsense MLIP variant c.1825A>T; p.Lys609Ter. Another individual from this pedigree, who had sinus arrhythmia and for whom creatine kinase level was not available, was also homozygous for this variant. CONCLUSIONS: Our findings suggest that biallelic truncating variants in MLIP result in myopathy characterized by hyperCKemia. Moreover, these cases of MLIP-related disease may indicate that at least in some instances this condition is associated with muscle decompensation and fatigability during low-to-moderate intensity muscle exertion as well as possible cardiac involvement.


Subject(s)
Cardiomyopathies , Muscular Diseases , Adaptation, Physiological , Animals , Humans , Muscular Diseases/genetics , Myalgia , Pedigree
12.
J Pediatr Gastroenterol Nutr ; 75(3): 244-251, 2022 09 01.
Article in English | MEDLINE | ID: mdl-35687535

ABSTRACT

OBJECTIVES: Severe acute respiratory syndrome coronavirus 2, the novel coronavirus responsible for coronavirus disease (COVID-19), has been a major cause of morbidity and mortality worldwide. Gastrointestinal and hepatic manifestations during acute disease have been reported extensively in the literature. Post-COVID-19 cholangiopathy has been increasingly reported in adults. In children, data are sparse. Our aim was to describe pediatric patients who recovered from COVID-19 and later presented with liver injury. METHODS: This is a retrospective case series study of pediatric patients with post-COVID-19 liver manifestations. We collected data on demographics, medical history, clinical presentation, laboratory results, imaging, histology, treatment, and outcome. RESULTS: We report 5 pediatric patients who recovered from COVID-19 and later presented with liver injury. Two types of clinical presentation were distinguishable. Two infants aged 3 and 5 months, previously healthy, presented with acute liver failure that rapidly progressed to liver transplantation. Their liver explant showed massive necrosis with cholangiolar proliferation and lymphocytic infiltrate. Three children, 2 aged 8 years and 1 aged 13 years, presented with hepatitis with cholestasis. Two children had a liver biopsy significant for lymphocytic portal and parenchyma inflammation, along with bile duct proliferations. All 3 were started on steroid treatment; liver enzymes improved, and they were weaned successfully from treatment. For all 5 patients, extensive etiology workup for infectious and metabolic etiologies was negative. CONCLUSIONS: We report 2 distinct patterns of potentially long COVID-19 liver manifestations in children with common clinical, radiological, and histopathological characteristics after a thorough workup excluded other known etiologies.


Subject(s)
COVID-19 , Liver Failure, Acute , Adolescent , COVID-19/complications , Child , Humans , Infant , Liver/pathology , Liver Failure, Acute/pathology , Retrospective Studies , SARS-CoV-2 , Post-Acute COVID-19 Syndrome
13.
Platelets ; 33(4): 645-648, 2022 May 19.
Article in English | MEDLINE | ID: mdl-35130804

ABSTRACT

The transcription factor MEIS1 (myeloid ectotrophic insertion site 1) is crucial for the maintenance of hematopoietic stem cells and for megakaryopoiesis. Germline variants in MEIS1 are associated with restless-leg syndrome, but were not previously shown to cause cytopenias. This is the first report of a patient with congenital thrombocytopenia associated with a sequence variant in MEIS1, presenting with early onset severe thrombocytopenia and mild signs of bone marrow stress. Whole exome sequencing revealed a de novo monoallelic splice site variant in MEIS1, NM_002398.3:exon4:c.432 + 5 G > C, leading to a premature stop codon. We propose that heterozygous mutations in MEIS1 may cause congenital thrombocytopenia.


Subject(s)
Thrombocytopenia , Transcription Factors , Gene Expression Regulation , Humans , Myeloid Ecotropic Viral Integration Site 1 Protein/genetics , Thrombocytopenia/genetics , Thrombopoiesis/genetics , Transcription Factors/genetics
14.
Prenat Diagn ; 42(6): 717-724, 2022 05.
Article in English | MEDLINE | ID: mdl-35032046

ABSTRACT

OBJECTIVE: Prenatal exome sequencing (ES) is currently indicated for fetal malformations. Some neurocognitive genetic disorders may not have a prenatal phenotype. We assessed the prevalence of prenatally detectable phenotypes among patients with neurocognitive syndromes diagnosed postnatally by ES. METHODS: The medical files of a cohort of 138 patients diagnosed postnatally with a neurocognitive disorder using ES were reviewed for prenatal sonographic data. The Online Mendelian Inheritance in Man (OMIM) database was searched for prenatally detectable phenotypes for all genes identified. RESULTS: Prenatal imaging data were available for 122 cases. Of these, 29 (23.75%) had fetal structural abnormalities and another 29 had other ultrasound abnormalities (fetal growth restriction, polyhydramnios, elevated nuchal translucency). In 30 patients, structural aberrations that were not diagnosed prenatally were detected at birth; in 21 (17.2%), the abnormalities could theoretically be detected prenatally by third-trimester/targeted scans. According to OMIM, 55.9% of the diagnosed genes were not associated with structural anomalies. CONCLUSIONS: Most patients (52.5%) with postnatally diagnosed neurocognitive disorders did not have prenatal sonographic findings indicating prenatal ES should be considered. The prevalence of specific prenatal phenotypes such as fetal growth restriction and polyhydramnios in our cohort suggests that additional prenatal findings should be assessed as possible indications for prenatal ES.


Subject(s)
Polyhydramnios , Prenatal Diagnosis , Cohort Studies , Exome , Female , Fetal Growth Retardation/diagnostic imaging , Fetal Growth Retardation/epidemiology , Humans , Phenotype , Polyhydramnios/diagnostic imaging , Polyhydramnios/epidemiology , Polyhydramnios/genetics , Pregnancy , Prenatal Diagnosis/methods , Prevalence , Ultrasonography, Prenatal/methods
15.
Genet Med ; 23(6): 1095-1100, 2021 06.
Article in English | MEDLINE | ID: mdl-33473205

ABSTRACT

PURPOSE: To investigate the effectiveness of phenotype-based search approaches using publicly available online databases. METHODS: We included consecutively solved cases from our exome database. For each case, the combination of Human Phenotype Ontology terms reported by the referring clinician was used to perform a search in three commonly used databases: OMIM (first 300 results), Phenolyzer (first 300 results), and Mendelian (all 100 results). RESULTS: One hundred cases were included (43 females; mean age: 10 years). The actual molecular diagnosis identified through exome sequencing was not included in the search results of any of the queried databases in 33% of cases. In 85% of cases it was not found within the top five search results. When included, its median rank was 61 (range: 1-295), 21 (1-270), and 29 (1-92) in OMIM, Phenolyzer and Mendelian, respectively. CONCLUSION: This study demonstrates that, in most cases, phenotype-based search approaches using public online databases is ineffective in providing a probable diagnosis for Mendelian conditions. Genotype-first approach through molecular-guided diagnostics with backward phenotyping may be a more appropriate approach for these disorders, unless a specific diagnosis is considered a priori based on highly unique phenotypic features or a specific facial gestalt.


Subject(s)
Databases, Genetic , Exome , Child , Databases, Factual , Exome/genetics , Female , Genotype , Humans , Phenotype , Exome Sequencing
16.
Genet Med ; 23(1): 215-221, 2021 01.
Article in English | MEDLINE | ID: mdl-32801363

ABSTRACT

PURPOSE: Clinical data provided to genetic testing laboratories are frequently scarce. Our purpose was to evaluate clinical scenarios where phenotypic refinement in proband's family members might impact exome data interpretation. METHODS: Of 614 exomes, 209 were diagnostic and included in this study. Phenotypic information was gathered by the variant interpretation team from genetic counseling letters and images. If a discrepancy between reported clinical findings and presumably disease-causing variant segregation was observed, referring clinicians were contacted for phenotypic clarification. RESULTS: In 16/209 (7.7%) cases, phenotypic refinement was important due to (1) lack of cosegregation of disease-causing variant with the reported phenotype; (2) identification of different disorders with overlapping symptoms in the same family; (3) similar features in proband and family members, but molecular cause identified in proband only; and (4) previously unrecognized maternal condition causative of child's phenotype. As a result of phenotypic clarification, in 12/16 (75%) cases definition of affected versus unaffected status in one of the family members has changed, and in one case variant classification has changed. CONCLUSION: Detailed description of phenotypes in family members including differences in clinical presentations, even if subtle, are important in exome interpretation and should be communicated to the variant interpretation team.


Subject(s)
Exome , Child , Exome/genetics , Genotype , Humans , Pedigree , Phenotype , Exome Sequencing
17.
Genet Med ; 23(2): 352-362, 2021 02.
Article in English | MEDLINE | ID: mdl-33106617

ABSTRACT

PURPOSE: Neurodevelopmental disorders (NDD) caused by protein phosphatase 2A (PP2A) dysfunction have mainly been associated with de novo variants in PPP2R5D and PPP2CA, and more rarely in PPP2R1A. Here, we aimed to better understand the latter by characterizing 30 individuals with de novo and often recurrent variants in this PP2A scaffolding Aα subunit. METHODS: Most cases were identified through routine clinical diagnostics. Variants were biochemically characterized for phosphatase activity and interaction with other PP2A subunits. RESULTS: We describe 30 individuals with 16 different variants in PPP2R1A, 21 of whom had variants not previously reported. The severity of developmental delay ranged from mild learning problems to severe intellectual disability (ID) with or without epilepsy. Common features were language delay, hypotonia, and hypermobile joints. Macrocephaly was only seen in individuals without B55α subunit-binding deficit, and these patients had less severe ID and no seizures. Biochemically more disruptive variants with impaired B55α but increased striatin binding were associated with profound ID, epilepsy, corpus callosum hypoplasia, and sometimes microcephaly. CONCLUSION: We significantly expand the phenotypic spectrum of PPP2R1A-related NDD, revealing a broader clinical presentation of the patients and that the functional consequences of the variants are more diverse than previously reported.


Subject(s)
Intellectual Disability , Microcephaly , Neurodevelopmental Disorders , Humans , Intellectual Disability/genetics , Muscle Hypotonia , Neurodevelopmental Disorders/epidemiology , Neurodevelopmental Disorders/genetics , Protein Phosphatase 2/genetics , Transcription Factors
18.
Am J Med Genet A ; 185(3): 901-908, 2021 03.
Article in English | MEDLINE | ID: mdl-33393734

ABSTRACT

A male patient with a de novo mutation in the YWHAG gene and mild phenotype is presented. He had normal delivery and normal development, with normal speech and social milestones. At the age of 9 months, myoclonic seizures started, with generalized epileptiform discharges. The child responded well to levetiracetam monotherapy with complete seizure resolution. Levetiracetam was stopped and he remained seizure-free for 10 months. His development was appropriate for age according to psychological evaluation and he attended a regular kindergarten. At the age of approximately 4 years, the seizures reappeared with different semiology of staring with eye blinking. Electroencephalogram (EEG) showed multifocal spikes. Brain magnetic resonance imaging did not reveal any structural abnormality. Genetic analysis revealed a de novo likely pathogenic missense variant in the YWHAG gene (c.619G>A p.Glu207Lys). We compared our case to the other cases published in the literature. Our case is unique in its seizure semiology and evolution of EEG. Moreover, in contrast to our case, the majority of cases described in the literature have dysmorphism and intellectual disability or autistic spectrum disorder. This report emphasizes the phenotypic heterogeneity of YWHAG mutation as is the case in other developmental encephalopathies.


Subject(s)
14-3-3 Proteins/genetics , Electroencephalography , Epilepsies, Myoclonic/genetics , Mutation, Missense , Amino Acid Substitution , Anticonvulsants/therapeutic use , Child, Preschool , Diagnosis, Differential , Epilepsies, Myoclonic/diagnosis , Epilepsies, Myoclonic/drug therapy , Humans , Levetiracetam/therapeutic use , Magnetic Resonance Imaging , Male , Neuroimaging , Phenotype , Valproic Acid/therapeutic use , Exome Sequencing
19.
Prenat Diagn ; 41(6): 701-707, 2021 May.
Article in English | MEDLINE | ID: mdl-33686681

ABSTRACT

OBJECTIVE: Laboratories performing prenatal exome sequencing (ES) frequently limit analysis to predetermined gene lists. We used a diagnostic postnatal ES cohort to assess how many of the genes diagnosed are not included in a number of select fixed lists used for prenatal diagnosis. METHODS: Of 601 postnatal ES tests, pathogenic variants related to neurodevelopmental disorders were detected in 138 probands. We evaluated if causative genes were present in the following: (1) Developmental Disorders Genotype-Phenotype database list, (2) a commercial laboratory list for prenatal ES, (3) the PanelApp fetal anomalies panel, and (4) a published list used for prenatal diagnosis by ES (Prenatal Assessment of Genomes and Exomes study). RESULTS: The percentages of cases where the diagnosed gene was not included in the selected four lists were; 11.6%, 17.24%, 23.2%, and 10.9%, respectively. In 13/138 (9.4%) cases, the causative gene was not included in any of the lists; in 4/13 (∼30%) cases noninclusion was explained by a relatively recent discovery of gene-phenotype association. CONCLUSIONS: A significant number of genes related to neurocognitive phenotypes are not included in some of the lists used for prenatal ES data interpretation. These are not only genes related to recently discovered disorders, but also genes with well-established gene-phenotype.


Subject(s)
Exome Sequencing/standards , Noninvasive Prenatal Testing/standards , Female , Fetus , Humans , Noninvasive Prenatal Testing/methods , Noninvasive Prenatal Testing/statistics & numerical data , Pregnancy , Exome Sequencing/methods , Exome Sequencing/statistics & numerical data
20.
J Med Genet ; 57(7): 505-508, 2020 07.
Article in English | MEDLINE | ID: mdl-31501241

ABSTRACT

Biallelic mutations in any of the four mismatch repair genes MSH2, MSH6, MLH1 and PMS2 result in one of the most aggressive childhood cancer predisposition syndromes, termed constitutional mismatch repair deficiency (CMMRD) syndrome. In addition to a very high tumour risk, the CMMRD phenotype is often characterised by the presence of signs reminiscent of neurofibromatosis type 1. Although paediatric systemic lupus erythematosus (pSLE) has been reported so far in three patients with CMMRD, it has not been considered a diagnostic feature of the syndrome. We report here two additional female patients with pSLE and CMMRD due to biallelic pathogenic variants in MSH6 Hence, there are a total of five out of approximately 200 (2.5%) currently reported patients with CMMRD that also have pSLE, suggesting pSLE should raise the suspicion of a diagnosis of CMMRD, especially if supported by additional indicative features.


Subject(s)
Brain Neoplasms/genetics , Colorectal Neoplasms/genetics , DNA-Binding Proteins/genetics , Lupus Erythematosus, Systemic/genetics , Neoplastic Syndromes, Hereditary/genetics , Neurofibromatosis 1/genetics , Brain Neoplasms/complications , Brain Neoplasms/pathology , Child , Child, Preschool , Colorectal Neoplasms/complications , Colorectal Neoplasms/pathology , DNA Mismatch Repair/genetics , Female , Humans , Lupus Erythematosus, Systemic/complications , Lupus Erythematosus, Systemic/pathology , Mutation , Neoplastic Syndromes, Hereditary/complications , Neoplastic Syndromes, Hereditary/pathology , Neurofibromatosis 1/complications , Neurofibromatosis 1/pathology , Pediatrics , Phenotype
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