Hyperammonemia Due to a Mutant Enzyme of Ornithine Transcarbamylase

Matsuda, Ichiro; Arashima, Shinichiro; Nambu, Haruo; Takekoshi, Yasuo; Anakura, Michiya

doi:10.1542/peds.48.4.595

Cited by 42 publications

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“…The normal hepatic OCT observed in our study was supported by the serum urea levels and the amino acid pattern. Elevation of serum urea and reduction of glutamine and lysine, and a normal level of glutamate in severe and less severe Zn-deficient animals, are in conflict with the observation for congenital OCT deficient patients for whom characteristic findings in the serum were normal or sometimes included lower levels of urea and elevated levelsof glutamate, glutamine, and lysine (13,14). Our Experimental groups mU/g wet weight mU/mg protein observation is comparable to that of Hsu et al (5) who found increased urea excretion in Zn-deficient rats and reported that this was attributable to protein catabolism associated with elevated arginase activity.…”

Section: Enzyme Studymentioning

confidence: 98%

Effects of Dietary Zinc Deficiency on Hepatic Ornithine Carbamoyltransferase and Alcohol Dehydrogenase Activities in Rats

Indo,

Nagata,

Higashi

et al. 1985

J. pediatr. gastroenterol. nutr.

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Hepatic ornithine carbamoyltransferase (OCT) and alcohol dehydrogenase (ADH) activities were measured in six groups of rats: (A) fed a severe zinc‐(Zn‐) deficient diet (1.98 ppm) for 5 weeks; (B) pair‐fed control for group (A); (C) fed a less severe Zn‐deficient diet (6.10 ppm) for 5 weeks; (D) pair‐fed control for group (C); (E) fed a Zn‐supplemented control diet (90.4 ppm) for 5 weeks; and (F) first fed the severe Zn‐deficient diet for 5 weeks and then replaced on the Zn‐supplemented control diet until a body weight corresponding to the final weight of group (E) was obtained. Hepatic OCT was similar in all these six groups. On the contrary, hepatic ADH was significantly reduced in groups (A) and (C) and in each of the corresponding pair‐fed groups, (B) and (D). No differences were found between groups (A) and (B) or between groups (C) and (D). In group (F), ADH activity improved to a level equivalent to that in group (E). The changes in ADH activities were accompanied by changes in the hepatic Zn content. Thus, it is clear that: (1) the hepatic Zn content may not be affected by the amount of Zn intake alone, but by the combination of Zn and food intake; and (2) ADH, and not OCT, reflected the hepatic Zn content.

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Section: Enzyme Studymentioning

confidence: 98%

Effects of Dietary Zinc Deficiency on Hepatic Ornithine Carbamoyltransferase and Alcohol Dehydrogenase Activities in Rats

Indo,

Nagata,

Higashi

et al. 1985

J. pediatr. gastroenterol. nutr.

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Detection of Urea Cycle Enzymopathies in Childhood

Trauner¹,

Self²

1984

Archives of Neurology

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The ornithine transcarbamylase (OTC) gene: Mutations in 50 Japanese families with OTC deficiency

Matsuda

Tanase

1997

Am. J. Med. Genet.

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Mutations in the OTC gene in 50 Japanese families with OTC deficiency were reviewed in relation to the phenotype of the patients and predicted structure of the mutant enzyme. Similar to other X-linked diseases, mutant alleles in OTC deficiency are highly heterogeneous. Mutations observed in male patients with neonatal onset of the disease included base insertion/deletion, exon skipping, and nonsense and missense mutations in exon 4, 5, 6, or 7. OTC activity was essentially undetectable in this group of patients. These mutations possibly resulted in unstable mRNA or truncated protein, or involved the active site or core domain of the enzyme leading to structural changes. In male patients with late onset, abnormalities observed were missense mutations in exons 2, 4, 8, 9, and 10, and missense mutations plus donor site errors involving exons 4, 5, and 6. OTC activity in these patients was 8.1 +/- 6.3% of the control and most mutations occurred on the surface of the protein. In female patients, age at onset ranged from 19 months to 7 years, depending on residual OTC activities (4.5 to 33% of the control). Most mutations in this group were similar to those seen in male patients with neonatal onset, i.e., nonsense and missense mutations in exons 5 and 6, and exon skipping, leading to null enzyme activity. These collective data can serve for genetic counseling and monitoring in prenatal care.

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Hyperammonemia Due to a Mutant Enzyme of Ornithine Transcarbamylase

Abstract: In a case of congenital hyperammonemia described in an 8½-month-old girl, elevated blood ammonia was shown to result from a mutant enzyme of ornithine transcarbamylase. An in vitro study indicated a decrease in affinity of the enzyme for carbamyl phosphate but not for ornithine.

Cited by 42 publications

References 0 publications

Effects of Dietary Zinc Deficiency on Hepatic Ornithine Carbamoyltransferase and Alcohol Dehydrogenase Activities in Rats

Effects of Dietary Zinc Deficiency on Hepatic Ornithine Carbamoyltransferase and Alcohol Dehydrogenase Activities in Rats

Detection of Urea Cycle Enzymopathies in Childhood

The ornithine transcarbamylase (OTC) gene: Mutations in 50 Japanese families with OTC deficiency

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