Akira Hata

A novel missense mutation in exon 8 of the ornithine transcarbamylase gene in two unrelated male patients with mild ornithine transcarbamylase deficiency

SummaryWe studied two unrelated male probands with mild ornithine transcarbamylase (OTC) (E.G.2.1.3.3) deficiency presenting a similar clinical course. Previous analyses of their liver OTCs also revealed similar properties. To identify the underlying molecular defects, we first cloned the entire coding region of the OTC gene from one proband and found a single base-substitution (C to T) leading to the substitution of tryptophan for arginine at amino acid position 277. Using a genomic amplification technique followed by allele specific oligonucleotide hybridization, we identified the same point mutation in the OTC gene of the other proband. We observed the presence of the mutation among family members in at least three generations, and in one asymptomatic hemizygous sibling in each family.

Immunochemical analysis of prolidase deficiency and molecular cloning of cDNA for prolidase of human liver

Prolidase (imidodipeptidase, EC 3.4.13.9) splits imidodipeptides with C-terminal proline or hydroxyproline residues. In humans, prolidase activity that is absent or markedly decreased results in prolidase deficiency (McKusick 26413), a genetic disease transmitted through autosomal recessive inheritance (Scriver et al., 1983). This biochemical defect has been associated with mental retardation, imidodipeptiduria, and, in some instances, deep skin ulcers (Ogata et al., 1981). The properties of prolidase from mammalian, including human, tissues have been reported. Most of the evidence obtained indicates that prolidase is a ubiquitous enzyme whose substrate specificity is restricted to imidodipeptides (Endo et al., 1981, Yoshimoto et al., 1983). However, no immunological analysis of human prolidase with a specific antibody has yet been described and the nature of the mutation has not been analysed at the molecular level. In this study, we isolated human prolidase and prepared monoclonal and polyclonal antibody. We were able to demonstrate the absence of the subunit of prolidase in a patient with prolidase deficiency. Further, a cDNA expression bank of human liver Was screened immunologically by using antibody against prolidase and a cDNA clone for the enzyme was isolated and identified.

Heterogeneous phenotypes of Japanese cases with a growth hormone gene deletion

SummaryWe studied four Japanese patients with isolated growth hormone (hGH) deficiency from three different families. There was consanguinity in two of the three families, and three patients were second cousins. Each patient was homozygous for a deletion of approximately 7.5 kilobases, which included the hGH-N gene. The deletions in three patients belonging to two different families were associated with the same restriction fragment length polymorphism haplotype, while the deletion of the other patient was associated with a different haplotype. All patients were treated with injections of pituitary hGH. The response to the therapy differed among them, that is, two patients belonging to different families showed a poor response together with the presence of anti-hGH antibodies, while the other two patients belonging to the same family showed a rather good response together with the absence of such antibodies. It is suggested that the production of anti-hGH antibodies is not solely due to the gene deletion, but that an unknown immunological disposition might also be involved.

Deduced amino acid sequence of human prolidase and molecular analyses of prolidase deficiency

Prolidase (peptidase D, imidodipeptidase, EC 3.4.13.9) splits dipeptides with a prolyl residue at the carboxy-terminal position. Deficiency of prolidase (McKusick 26413) is an autosomal recessive disorder characterized by mental retardation, various skin lesions and abnormalities of collagenous tissues. The nucleotide sequence of the cDNA inserts and partial amino acid sequence of the peptides allow us to deduce the amino acid sequence of the subunit protein of human prolidase. The cDNA inserts are used for Northern blot analyses of mRNA obtained from patients with prolidase deficiency

Structure of the ornithine transcarbamylase (OTC) gene and DNA diagnosis of OTC deficiency

Complementary and genomic DNA clones corresponding to human ornithine transcarbamylase (OTC) have been isolated and analyzed. Restriction fragment length polymorphisms (RFCPs) on OTC gene locus were analyzed in Japanese female population. Based on these data, a prenatal diagnosis of OTC deficiency was carried out in a risk family. A C-to-T substitution was found in exon 5 of OTC gene is an another female patient.

Study of a female patient with ornithine transcarbamylase deficiency: Detection of a nonsense mutation

Ornithine transcarbamylase (OTC) (EC 2.1.3.3) deficiency is the most common inborn error of the urea cycle and shows an X-linked inheritance. We report herein the molecular basis of an alteration in the OTC gene of a female patient with mild OTC deficiency. By in vitro amplification and sequencing of the amplified genomic DNA, we found a C-to-T substitution in exon 5 of the OTC gene. Oligodeoxyribonucleotide hybridization procedures were used for confirmation

Attempts to Investigate the Molecular Basis of Urea Cycle Disorders

Five enzymes, carbamylphosphate synthetase, orinithine carbamoyl transferase (OCT), argininosuccinate synthetase (AS), argininosuccinate lyase and arginase, are involved in the synthesis of urea in the liver tissue. Enzyme deficiencies of inherited origin have been reported for each enzyme, in Japan as well as in other countries. As in other countries, the most common type is OCT deficiency. The second most common in Japan is AS synthetase deficiency (citrullinemia), especially of the variant type. Presentation and discussion focus on these two diseases.