伊藤 哲哉

Background: Female patients with ornithine transcarbamylase deficiency (OTCD) show a wide range of clinical severity, from asymptomatic to lethal hyperammonemia. It is important to establish a simple method to distinguish symptomatic from asymptomatic patients. Methods: Uracil and orotic acid concentrations were analyzed in three female patients with OTCD at both the hyperammonemia-attack and interval stages. These concentrations were compared with those in asymptomatic female patients reported previously. Results: Uracil concentrations in symptomatic female patients were uniformly higher than those in asymptomatic female patients at both the hyperammonemia-attack and interval stages. Conclusion: Uracil may present a useful index for detecting OTCD female patients who are destined to suffer from hyperammonemia attack. Further data on uracil concentrations are necessary to establish the threshold for distinguishing symptomatic from asymptomatic subjects.

Ornithine aminotransferase (OAT) deficiency (MIM: 258870) is a rare congenital metabolic disorder characterized by gyrate atrophy of the choroid and retina. Here, we report a 37-year-old male with gyrate atrophy of the choroid and retina who has been treated for 18 years. At the age of 7 years, the patient consulted an ophthalmologist due to progressive loss of vision. A large atrophied area was observed in his retina, and OAT deficiency was suspected. At the age of 19 years, amino acid analysis revealed high serum ornithine levels (1140 nmol/ml), with the normal range being 40-100 nmol/ml. He was treated with vitamin B-6 300 mg/day for 6 months, which successfully reduced his serum ornithine levels by 20-30%. For 18 years since, his serum ornithine levels have been maintained with vitamin B-6 medication. There was no further impairment of vision or increase in the atrophied area, as judged by ophthalmoscopic examination. OAT activity was undetected in white blood cells of the patient and was 105% and 45% of normal values in his wife and son, respectively. OAT gene analysis revealed a novel mutation of Gly237Asp in exon 7 (710G > A) in both alleles of the patient, while his son was a heterozygote for the mutation. Notably, this novel mutation is associated with a vitamin B-6-responsive phenotype. Therefore, early diagnosis and treatment with vitamin B-6 may prevent loss of vision in some patients with OAT deficiency.

Objective: To clarify the pathogenesis of transient hyper-17α- hydroxyprogesteronemia, we initiated a laboratory investigation in a pre-term infant with persistently high serum 17α-hydroxyprogesterone (17-OHP) until 2 months of age. Methods: Serum 17-OHP level was measured by high-performance liquid chromatography and radioimmunoassay, and gene analysis of CYP21A2 (21-hydroxylase) was performed. Result: Serum 17-OHP level on the 29th day of life was 25.4 ng/ml, and the urinary steroid profile showed low pregnanetriolone. Gene analysis of 21-hydroxylase disclosed no mutation, and 17-OHP normalized by 3 months of age without specific treatment. Conclusion: Transient elevations in 17-OHP, which do not appear related to cross-reactions with products of a residual fetal adrenal cortex, may occur in the first few months of life. Copyright © 2004 S. Karger AG, Basel.

A rapid yet reliable chemical diagnosis for dihydropyrimidine dehydrogenase (DHPD) deficiency, and possibly dihydropyrimidinase (DHP) deficiency in cancer patients, prior to therapy with pyrimidine analogues such as 5-fluorouracil, is desired for prevention of severe side-effects by these drugs. We have reported the basic separation and quantitation technology for pyrimidine metabolites using gas chromatography-mass spectrometry. A proposal to use the number (n) of standard deviations (SD) above the normal mean, as the index of the excessive urinary excretion of the metabolites appears not to be commonly used. When used, the values were too small, such as two or three, even in genetic disorders. Here, we applied the method to 11 urine specimens from proven cases including two DHP carriers and proved how specific the method is, because "n"-values were markedly large for thymine (T), uracil (U) and/or dihydrothymine (DHT) and dihydrouracil (DHU). In three cases with DHPD deficiency, two were siblings, one with symptoms and the other without, n was 12 for T and 5.9 for U, and 5-hydroxymethyluracil was distinctly detected. These values indicate that the nature of genetic mutation relates closely to the degree of metabolite accumulation in pyrimidine disorders. In six patients with DHP deficiency, n was 8.4-12 for DHT and 7.2-11 for DHU. Many mutations are known for both genes and the assay of residual enzyme activity may be time-consuming or invasive especially for those with DHP deficiency. Thus, this noninvasive yet comprehensive urinalysis has great value for those without a family history, as the first trial, before DNA or the enzyme assay. Our findings again raise the question whether the metabolic block really causes the symptoms found in pyrimidine disorders. (C) 2003 Elsevier Science B.V. All rights reserved.