Project description:Combined deficiency of factor V (FV) and FVIII (F5F8D) is an autosomal recessive bleeding disorder characterized by simultaneous decreases of both coagulation factors. This review summarizes recent reports on the clinical presentations, treatments, and molecular mechanism of F5F8D. Genetic studies identified LMAN1 and MCFD2 as causative genes for this disorder, revealing a previously unknown intracellular transport pathway shared by the two important blood coagulation factors. LMAN1 and MCFD2 form a Ca2+-dependent cargo receptor complex that functions in the transport of FV/FVIII from the endoplasmic reticulum (ER) to the Golgi. Disrupting the LMAN1-MCFD2 receptor, complex formation is the primary molecular defect of missense mutations leading to F5F8D. The EF-hand domains of MCFD2 are necessary and sufficient for the interactions with both LMAN1 and FV/FVIII. Similarly, the carbohydrate recognition domain of LMAN1 contains distinct and separable binding sites for both MCFD2 and FV/FVIII. Therefore, FV and FVIII likely carry duel sorting signals that are separately recognized by LMAN1 and MCFD2 and necessary for the efficient ER-to-Golgi transport. FV and FVIII likely bind LMAN1 through the high-mannose N-linked glycans under the higher Ca2+ conditions in the ER and dissociate in the lower Ca2+ environment of the ER-Golgi intermediate compartment.
Project description:Combined oxidative phosphorylation deficiency-17 (COXPD-17) is very rare and is caused by homozygous or compound heterozygous mutations in the ELAC2 gene on chromosome 17p12. The ELAC2 gene functions as a mitochondrial tRNA processing gene, and only 4 different pathogenic mutations have been reported in ELAC2-associated mitochondrial dysfunction involving oxidative phosphorylation. Affected patients show various clinical symptoms and prognosis, depending on the genotype. We report a novel mutation in the ELAC2 gene (c.95C>G [p.Pro32Arg], het), in an infant with COXPD-17 who presented with encephalopathy including central apnea and intractable epilepsy, and growth and developmental retardation. During hospitalization, consistently elevated serum lactic acid levels were noted, indicative of mitochondrial dysfunction. The patient suddenly died of shock of unknown cause at 5 months of age. This is the first case report of COXPD-17 in Korea and was diagnosed based on clinical characteristics and genetic analysis.
Project description:We report the case of a two-year-old full-term girl of consanguineous Saudi parents, who had a history of poor sucking, hypotonia, and bilateral ptosis, as well as recurrent pediatric intensive care unit (PICU) admissions with apnea and global developmental delay and unremarkable family history. A genetic study was conducted and whole exome sequencing (WES) identified a likely pathogenic homozygous variant c.842C>T p.(Ala281Val) in the SLC25A1 gene. This finding is consistent with the genetic diagnosis of autosomal recessive combined D-2- and L-2-hydroxyglutaric aciduria (D/L-2-HGA). Genetic testing results suggested a diagnosis of congenital myasthenic syndrome (CMS) type 23 [Online Mendelian Inheritance in Man (OMIM) #618197]. CMS is a highly heterogeneous group of neuromuscular junction (NMJ) disorders clinically and genetically and compromises the safety margin required for reliable neuromuscular transmission. Fortunately, we suspected a CMS in our patient, and the initiation of management with pyridostigmine has substantially improved the patient's condition.
Project description:ObjectiveThe aim was to investigate the clinical characteristics and molecular pathogenic mechanism of twins with congenital factor V (FV) deficiency.MethodsWe comprehensively analyzed the clinical manifestations and laboratory test results of a set of twins and their parents and performed point mutation analysis with direct high-throughput exon sequencing.ResultsThe prothrombin time and activated partial thromboplastin time were prolonged for both probands, and the FV activity levels were 13.0% and 9.8%. Next-generation sequencing showed that the affected individuals harbored a paternal c.5113A>C (p.S1705R) and a maternal c.4949C>T (p.A1650V) heterozygous variants in the FV gene, which conformed to an autosomal recessive inheritance pattern. This is the first report of these point mutations. The older boy also had a congenital patent foramen ovale.ConclusionIn this set of twins, missense mutations of the FV gene were related to congenital FV deficiency but unrelated to the patent foramen ovale observed in the older boy.
Project description:Dihydropyrimidinase (DHP, EC 3.5.2.2) is the second enzyme of the pyrimidine degradation pathway and a deficiency of this enzyme is responsible for a rare inborn metabolic syndrome characterized by dihydropyrimidinuria. Here we report a cat with DHP deficiency, manifesting malnutrition, depression, vomiting, and hyperammonemia. A gas chromatographic-mass spectrometric analysis of urinary metabolic substances showed the presence of large amounts of dihydrouracil and dihydrothymine and moderate amounts of uracil and thymine, suggesting DHP deficiency. Analysis of the feline DPYS gene encoding DHP demonstrated that the cat was homozygous for the missense mutation c.1303G>A (p.G435R) in exon 8, which corresponds to a known mutation in a human patient with DHP deficiency. Population screening in 1,000 cats did not reveal any animal possessing this mutation, suggesting the prevalence of the mutant allele to be very low. This is the first report of naturally occurring DHP deficiency in animals and the cat represents a model of the human disease.
Project description:Coagulation factor VII (proconvertin) is one of the proteins starting the blood coagulation cascade. Plasma FVII concentration is regulated by different factors. A low level of FVII could also be a result of FVII deficiency (MIM# 227500), the rare autosomal recessive inherited disease caused by pathogenic variants in the F7 gene. The aim of this study was to describe a mutation spectrum of the F7 gene and genotype-phenotype relationship in patients with FVII deficiency in Russia for the first time. We studied the primary structure of the F7 gene of 54 unrelated patients with FVII deficiency by direct Sanger sequencing. Pathogenic variants in the F7 gene were detected in 37 (68.5%) of them. We identified 24 different mutations located mostly in the serine protease domain. Five pathogenic variants had never been reported before. A major mutation in the Russian population was c.1391delC (p. Pro464Hisfs*32), linked with rs36209567 and rs6046 functional polymorphisms, that is widely distributed in East Europe. As in other countries, the F7 genotypes poorly correlated with the severity of clinical manifestations but were quite well associated with FVII levels. Minor alleles of functional polymorphisms rs510335, rs5742910, rs561241, rs36209567, and rs6046 could also participate in the F7 genotype and influence FVII levels.
Project description:We characterized a 2.1-kb human cDNA with a 1362-bp (454-amino acid) open reading frame showing 70.3% amino acid identity to goose malonyl-CoA decarboxylase (MCD). We have identified two different homozygous mutations in human MCD (hMCD) by using RT-PCR analysis of fibroblast RNA from two previously reported consanguineous Scottish patients with MCD deficiency. The first mutation is a 442C-->G transversion resulting in a premature stop codon (S148X) in the N-terminal half of the protein. The second is a 13-bp insertion in the mature RNA, causing a frameshift with predicted protein truncation. This insertion is the result of an intronic mutation generating a novel splice acceptor sequence (IVS4-14A-->G). Both mutations were found to segregate appropriately within the families and were not found in 100 normal unrelated individuals. These mutations would be predicted to cause MCD deficiency, thus confirming this transcript as the hMCD ortholog. The peptide sequence of hMCD revealed a C-terminal peroxisomal targeting sequence (-SKL). This targeting signal appears to be functional in vivo, since the distribution of MCD enzymatic activity in rat liver homogenates-as measured by means of subcellular fractionation-strongly suggests that MCD is localized to peroxisomes in addition to the mitochondrial localization reported elsewhere. These data strongly support this cDNA as encoding human MCD, an important regulator of fatty acid metabolism.
Project description:Genitopatellar syndrome (GPS) is mainly characterized by an absence of patellae, congenital flexion contractures of the lower limbs, psychomotor retardation, and anomalies of the external genitalia and kidneys. We report an 18-year-old female with a novel heterozygous truncating mutation in exon 17 of the KAT6B gene [MC_000010.11:c.3603_3606 del, p.Arg1201fs]. This is the first report of typical GPS in a Japanese individual. The details of our findings may contribute to elucidating the mechanism underlying GPS-specific clinical features.