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1.
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.

2.
Cell Death Dis ; 15(5): 379, 2024 May 30.
Article in English | MEDLINE | ID: mdl-38816421

ABSTRACT

CSMD1 (Cub and Sushi Multiple Domains 1) is a well-recognized regulator of the complement cascade, an important component of the innate immune response. CSMD1 is highly expressed in the central nervous system (CNS) where emergent functions of the complement pathway modulate neural development and synaptic activity. While a genetic risk factor for neuropsychiatric disorders, the role of CSMD1 in neurodevelopmental disorders is unclear. Through international variant sharing, we identified inherited biallelic CSMD1 variants in eight individuals from six families of diverse ancestry who present with global developmental delay, intellectual disability, microcephaly, and polymicrogyria. We modeled CSMD1 loss-of-function (LOF) pathogenesis in early-stage forebrain organoids differentiated from CSMD1 knockout human embryonic stem cells (hESCs). We show that CSMD1 is necessary for neuroepithelial cytoarchitecture and synchronous differentiation. In summary, we identified a critical role for CSMD1 in brain development and biallelic CSMD1 variants as the molecular basis of a previously undefined neurodevelopmental disorder.


Subject(s)
Intellectual Disability , Membrane Proteins , Humans , Intellectual Disability/genetics , Intellectual Disability/pathology , Membrane Proteins/genetics , Membrane Proteins/metabolism , Female , Male , Neurodevelopmental Disorders/genetics , Alleles , Malformations of Cortical Development/genetics , Malformations of Cortical Development/pathology , Child , Child, Preschool , Cell Differentiation/genetics , Tumor Suppressor Proteins
3.
Arthritis Rheumatol ; 76(3): 444-454, 2024 Mar.
Article in English | MEDLINE | ID: mdl-37738164

ABSTRACT

OBJECTIVE: Cryopyrin-associated periodic syndromes (CAPS), also known as NLRP3-associated autoinflammatory diseases, are a spectrum of rare autoinflammatory diseases caused by gain-of-function variants in the NLRP3 gene, resulting in inflammasome hyperactivation and dysregulated release of interleukin-1ß (IL-1ß). Many patients with CAPS develop progressive sensorineural hearing loss (SNHL) because of cochlear autoinflammation, which may be the sole manifestation in rare cases. This study was undertaken to establish the suspected diagnosis of CAPS in a family presenting with autosomal-dominant progressive/acute SNHL and a novel missense variant in the NLRP3 gene of unknown significance (NM_001079821.3:c.1784G>A p.Ser595Asn). METHODS: We conducted an ex vivo functional assessment of the NLRP3 inflammasome in heterozygous individuals (n = 10) and healthy family members (n = 5). RESULTS: The assay revealed hyperactivation of the inflammasome among heterozygous individuals, supporting the hypothesis that this missense variant is a pathogenic gain-of-function variant. Administration of IL-1 receptor antagonist resulted in a substantial clinical improvement among pediatric patients, who exhibited near resolution of hearing impairment within 1 to 3 months of treatment. CONCLUSION: Our findings highlight the crucial role of early diagnosis and treatment with an anti-IL-1 agent in reversing cochlear damage. Furthermore, our results suggest that high- and ultrahigh-frequency ranges need to be included in the auditory assessment to enable early detection of subclinical SNHL. Finally, incorporating functional inflammasome assessment as part of the clinical evaluation could establish the diagnosis in inconclusive cases.


Subject(s)
Cryopyrin-Associated Periodic Syndromes , Hearing Loss , Child , Humans , Cryopyrin-Associated Periodic Syndromes/drug therapy , Cryopyrin-Associated Periodic Syndromes/genetics , Family , Hearing Loss/drug therapy , Hearing Loss/genetics , Hearing Loss/complications , Inflammasomes/genetics , NLR Family, Pyrin Domain-Containing 3 Protein/genetics
4.
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
5.
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
6.
Neuromuscul Disord ; 34: 32-40, 2024 Jan.
Article in English | MEDLINE | ID: mdl-38142473

ABSTRACT

We describe three patients with asymmetric congenital myopathy without definite nemaline bodies and one patient with severe nemaline myopathy. In all four patients, the phenotype had been caused by pathogenic missense variants in ACTA1 leading to the same amino acid change, p.(Gly247Arg). The three patients with milder myopathy were mosaic for their variants. In contrast, in the severely affected patient, the missense variant was present in a de novo, constitutional form. The grade of mosaicism in the three mosaic patients ranged between 20 % and 40 %. We speculate that the milder clinical and histological manifestations of the same ACTA1 variant in the patients with mosaicism reflect the lower abundance of mutant actin in their muscle tissue. Similarly, the asymmetry of body growth and muscle weakness may be a consequence of the affected cells being unevenly distributed. The partial improvement in muscle strength with age in patients with mosaicism might be due to an increased proportion over time of nuclei carrying and expressing two normal alleles.


Subject(s)
Muscular Diseases , Myopathies, Nemaline , Humans , Myopathies, Nemaline/genetics , Myopathies, Nemaline/pathology , Muscle, Skeletal/pathology , Actins/genetics , Mutation , Muscular Diseases/genetics , Amino Acids/genetics , Amino Acids/metabolism
7.
Gene ; 887: 147728, 2023 Dec 15.
Article in English | MEDLINE | ID: mdl-37634880

ABSTRACT

BACKGROUND: Wilson disease is caused by pathogenic variants in the ATP7B gene which encodes a copper-transporting ATPase. AIMS: Describe a common founder pathogenic variant among Bukharan Jews and to assess its prevalence, clinical features, and outcome. METHODS: The cohort consisted of patients of Bukharan Jewish descent diagnosed with Wilson disease at a tertiary pediatric medical center in 2013-2018. Clinical and genetic data were collected and analyzed. RESULTS: Six patients from 4 unrelated families who were homozygous for the c.3784G > T p.(Val1262Phe) pathogenic variant in ATP7B were identified. Five presented with elevated aminotransferase levels, and one, with acute liver failure. Mean age at diagnosis was 8.7 years (5-12.5). Serum ceruloplasmin level was extremely low in all patients (1.9-7 mg/dL; mean 3.2(. The variant was identified in a heterozygous state in 5/153 Bukharan Jews; 2/33 from our local exome database and 3/120 healthy unrelated Bukharan Jews in another cohort, for an estimated carrier frequency of ∼1:30. CONCLUSIONS: We report a common founder pathogenic variant in the ATP7B gene among Bukharan Jews associated with severe early-onset Wilson disease. Given the clinical severity, high frequency of the variant, and being a treatable disease, its inclusion in pre-symptomatic screening in the Bukharan Jewish community should be considered. Furthermore, WD should be part of future genetic newborn screening programs in Israel and worldwide, to enable early treatment and prevention of future life-threatening complications.


Subject(s)
Hepatolenticular Degeneration , Infant, Newborn , Humans , Child , Hepatolenticular Degeneration/genetics , Hepatolenticular Degeneration/epidemiology , Jews/genetics , Israel/epidemiology , Copper-Transporting ATPases/genetics , Genetic Testing , Heterozygote , Mutation
8.
Gene ; 874: 147483, 2023 Jul 20.
Article in English | MEDLINE | ID: mdl-37196891

ABSTRACT

Citrin deficiency is an autosomal recessive disorder associated with SLC25A13 gene pathogenic variants, with more than a hundred known at present. It manifests in neonates as failure to thrive and acute liver insufficiency. We herein describe a case of a 4-week-old infant who presented with insufficient weight gain and liver failure accompanied by hyperammonemia. She was diagnosed with Citrin deficiency after a thorough biochemical and molecular analysis including amino acid profile, DNA sequencing of genes of interest and RNA splice site evaluation, to reveal a yet unknown damaging variant of the SLC25A13 gene.


Subject(s)
Citrullinemia , Organic Anion Transporters , Infant, Newborn , Female , Humans , Infant , Citrullinemia/genetics , Mutation , Mitochondrial Membrane Transport Proteins/genetics , Base Sequence , Calcium-Binding Proteins/genetics , Organic Anion Transporters/genetics
9.
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
10.
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
11.
Ann Clin Transl Neurol ; 9(7): 1080-1089, 2022 07.
Article in English | MEDLINE | ID: mdl-35684946

ABSTRACT

The endoplasmic reticulum membrane protein complex subunit 10 (EMC10) is a highly conserved protein responsible for the post-translational insertion of tail-anchored membrane proteins into the endoplasmic reticulum in a defined topology. Two biallelic variants in EMC10 have previously been associated with a neurodevelopmental disorder. Utilizing exome sequencing and international data sharing we have identified 10 affected individuals from six independent families with five new biallelic loss-of-function and one previously reported recurrent EMC10 variants. This report expands the molecular and clinical spectrum of EMC10 deficiency, provides a comprehensive dysmorphological assessment and highlights an overlap between the clinical features of EMC10-and EMC1-related disease.


Subject(s)
Intellectual Disability , Membrane Proteins , Neurodevelopmental Disorders , Humans , Intellectual Disability/genetics , Membrane Proteins/genetics , Neurodevelopmental Disorders/genetics , Exome Sequencing
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.
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
14.
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
15.
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
17.
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
18.
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
19.
Metab Brain Dis ; 36(7): 2155-2167, 2021 10.
Article in English | MEDLINE | ID: mdl-33963976

ABSTRACT

Mucolipidosis type IV (MLIV; OMIM 252,650) is an autosomal recessive lysosomal disorder caused by mutations in MCOLN1. MLIV causes psychomotor impairment and progressive vision loss. The major hallmarks of postnatal brain MRI are hypomyelination and thin corpus callosum. Human brain pathology data is scarce and demonstrates storage of various inclusion bodies in all neuronal cell types. The current study describes novel fetal brain MRI and neuropathology findings in a fetus with MLIV. Fetal MRI was performed at 32 and 35 weeks of gestation due to an older sibling with spastic quadriparesis, visual impairment and hypomyelination. Following abnormal fetal MRI results, the parents requested termination of pregnancy according to Israeli regulations. Fetal autopsy was performed after approval of the high committee for pregnancy termination. A genetic diagnosis of MLIV was established in the fetus and sibling. Sequential fetal brain MRI showed progressive curvilinear hypointensities on T2-weighted images in the frontal deep white matter and a thin corpus callosum. Fetal brain pathology exhibited a thin corpus callosum and hypercellular white matter composed of reactive astrocytes and microglia, multifocal white matter abnormalities with mineralized deposits, and numerous aggregates of microglia with focal intracellular iron accumulation most prominent in the frontal lobes. This is the first description in the literature of brain MRI and neuropathology in a fetus with MLIV. The findings demonstrate prenatal white matter involvement with significant activation of microglia and astrocytes and impaired iron metabolism.


Subject(s)
Mucolipidoses , Transient Receptor Potential Channels , White Matter , Female , Humans , Iron/metabolism , Mucolipidoses/diagnostic imaging , Mucolipidoses/genetics , Pregnancy , Prenatal Diagnosis , Transient Receptor Potential Channels/genetics , Transient Receptor Potential Channels/metabolism , White Matter/metabolism
20.
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
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