Calcium (Ca
) is a universal second messenger involved in synaptogenesis and cell survival; consequently, its regulation is important for neurons. ATPase plasma membrane Ca
transporting 1 (ATP2B1) ...belongs to the family of ATP-driven calmodulin-dependent Ca
pumps that participate in the regulation of intracellular free Ca
. Here, we clinically describe a cohort of 12 unrelated individuals with variants in ATP2B1 and an overlapping phenotype of mild to moderate global development delay. Additional common symptoms include autism, seizures, and distal limb abnormalities. Nine probands harbor missense variants, seven of which were in specific functional domains, and three individuals have nonsense variants. 3D structural protein modeling suggested that the variants have a destabilizing effect on the protein. We performed Ca
imaging after introducing all nine missense variants in transfected HEK293 cells and showed that all variants lead to a significant decrease in Ca
export capacity compared with the wild-type construct, thus proving their pathogenicity. Furthermore, we observed for the same variant set an incorrect intracellular localization of ATP2B1. The genetic findings and the overlapping phenotype of the probands as well as the functional analyses imply that de novo variants in ATP2B1 lead to a monogenic form of neurodevelopmental disorder.
Inherited disorders of cobalamin (Cbl, vitamin B12) metabolism are rare causes of megaloblastic anemia and neurologic abnormalities. More prevalent in certain ethnic groups, these disorders occur ...despite adequate Cbl intake and usually result from abnormal vitamin cell transport or processing. Cubilin (CUBN, intrinsic factor-cobalamin receptor) is the intestinal receptor for the endocytosis of intrinsic factor-vitamin B12. Its gene is localized to chromosome 10p13 and mutations involving CUBN have been described in patients with congenital megaloblastic anemia. In this report, we describe a novel CUBN pathogenic variant in a child with megaloblastic anemia.
BackgroundVariants in HECW2 have recently been reported to cause a neurodevelopmental disorder with hypotonia, seizures and impaired language; however, only six variants have been reported and the ...clinical characteristics have only broadly been defined.MethodsMolecular and clinical data were collected from clinical and research cohorts. Massive parallel sequencing was performed and identified individuals with a HECW2-related neurodevelopmental disorder.ResultsWe identified 13 novel missense variants in HECW2 in 22 unpublished cases, of which 18 were confirmed to have a de novo variant. In addition, we reviewed the genotypes and phenotypes of previously reported and new cases with HECW2 variants (n=35 cases). All variants identified are missense, and the majority of likely pathogenic and pathogenic variants are located in or near the C-terminal HECT domain (88.2%). We identified several clustered variants and four recurrent variants (p.(Arg1191Gln);p.(Asn1199Lys);p.(Phe1327Ser);p.(Arg1330Trp)). Two variants, (p.(Arg1191Gln);p.(Arg1330Trp)), accounted for 22.9% and 20% of cases, respectively. Clinical characterisation suggests complete penetrance for hypotonia with or without spasticity (100%), developmental delay/intellectual disability (100%) and developmental language disorder (100%). Other common features are behavioural problems (88.9%), vision problems (83.9%), motor coordination/movement (75%) and gastrointestinal issues (70%). Seizures were present in 61.3% of individuals. Genotype-phenotype analysis shows that HECT domain variants are more frequently associated with cortical visual impairment and gastrointestinal issues. Seizures were only observed in individuals with variants in or near the HECT domain.ConclusionWe provide a comprehensive review and expansion of the genotypic and phenotypic spectrum of HECW2 disorders, aiding future molecular and clinical diagnosis and management.
Enzyme-based newborn screening for Mucopolysaccharidosis type I (MPS I) has a high false-positive rate due to the prevalence of pseudodeficiency alleles, often resulting in unnecessary and costly ...follow up. The glycosaminoglycans (GAGs), dermatan sulfate (DS) and heparan sulfate (HS) are both substrates for α-l-iduronidase (IDUA). These GAGs are elevated in patients with MPS I and have been shown to be promising biomarkers for both primary and second-tier testing. Since February 2016, we have measured DS and HS in 1213 specimens submitted on infants at risk for MPS I based on newborn screening. Molecular correlation was available for 157 of the tested cases. Samples from infants with MPS I confirmed by
molecular analysis all had significantly elevated levels of DS and HS compared to those with confirmed pseudodeficiency and/or heterozygosity. Analysis of our testing population and correlation with molecular results identified few discrepant outcomes and uncovered no evidence of false-negative cases. We have demonstrated that blood spot GAGs analysis accurately discriminates between patients with confirmed MPS I and false-positive cases due to pseudodeficiency or heterozygosity and increases the specificity of newborn screening for MPS I.
We describe 2 pediatric patients who presented to medical genetics clinic for evaluation and were incidentally found via array comparative genomic hybridization to have pathogenic copy number ...variations of cancer predisposition genes. We subsequently reviewed 3554 previous array comparative genomic hybridization results to estimate the frequency of similar incidental findings.
Craniofacial malformations are among the most common birth defects. Although most cases of orofacial clefting and craniosynostosis are isolated and sporadic, these abnormalities are associated with a ...wide range of genetic syndromes, and making the appropriate diagnosis can guide management and counseling. Patients with craniofacial malformation are best cared for in a multidisciplinary clinic that can coordinate the care delivered by a diverse team of providers.
Circadian clocks are critical modulators of metabolism. However, mechanistic links between cell autonomous clocks and metabolic processes remain largely unknown. Here, we report that expression of ...the biotin transporter slc5a6 gene is decreased in hearts of two distinct genetic mouse models of cardiomyocyte-specific circadian clock disruption i.e., cardiomyocyte-specific CLOCK mutant (CCM) and cardiomyocyte-specific BMAL1 knockout (CBK) mice. Biotinylation is an obligate posttranslational modification for five mammalian carboxylases: acetyl-CoA carboxylase α (ACCα), ACCβ, pyruvate carboxylase (PC), methylcrotonyl-CoA carboxylase (MCC), and propionyl-CoA carboxylase (PCC). We therefore hypothesized that the cardiomyocyte circadian clock impacts metabolism through biotinylation. Consistent with decreased slc5a6 expression, biotinylation of all carboxylases is significantly decreased (10-46%) in CCM and CBK hearts. In association with decreased biotinylated ACC, oleate oxidation rates are increased in both CCM and CBK hearts. Consistent with decreased biotinylated MCC, leucine oxidation rates are significantly decreased in both CCM and CBK hearts, whereas rates of protein synthesis are increased. Importantly, feeding CBK mice with a biotin-enriched diet for 6 wk normalized myocardial 1) ACC biotinylation and oleate oxidation rates; 2) PCC/MCC biotinylation (and partially restored leucine oxidation rates); and 3) net protein synthesis rates. Furthermore, data suggest that the RRAGD/mTOR/4E-BP1 signaling axis is chronically activated in CBK and CCM hearts. Finally we report that the hepatocyte circadian clock also regulates both slc5a6 expression and protein biotinylation in the liver. Collectively, these findings suggest that biotinylation is a novel mechanism by which cell autonomous circadian clocks influence metabolic pathways.
Partial trisomy 21: a fifty-year follow-up visit Hamm, J Austin; Carroll, Andrew J; Mikhail, Fady M ...
American journal of medical genetics. Part A,
July 2015, Letnik:
167, Številka:
7
Journal Article
Recenzirano
We describe a clinical encounter with family members that carry a balanced translocation involving chromosomes 15 and 21 roughly 50 years after the proband was diagnosed with partial trisomy 21 due ...to an unbalanced translocation. We discuss how these chromosomal rearrangements have impacted the lives of these individuals, and how they responded to revisiting their diagnoses after using updated cytogenetic techniques including high resolution chromosome banding and array comparative genomic hybridization.
PDF
