Tohoku J. Exp. Med., 2005, 205(4)

Vitamin B₆-Responsive Ornithine Aminotransferase Deficiency with a Novel Mutation G237D

YUMIKO OHKUBO, AKIHITO UETA, TETSUYA ITO, SATOSHI SUMI, MARI YAMADA,¹ KATSUKO OZAWA² and HAJIME TOGARI

Department of Pediatrics, Neonatology and Congenital Disorders, Nagoya City University, Graduate School of Medical Sciences, Nagoya, ¹Department of Ophthalmology, Higashi Municipal Hospital of Nagoya, Nagoya, and ²Department of Ophthalmology, Mainichi Clinic, Nagoya, Japan

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 B₆ 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 B₆ 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 B6-responsive phenotype. Therefore, early diagnosis and treatment with vitamin B6 may prevent loss of vision in some patients with OAT deficiency.

keywords —— ornithine aminotransferase; gyrate atrophy; hyperornithinemia; vitamin B₆

© 2005 Tohoku University Medical Press

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Correspondence: Yumiko Ohkubo, Department of Neonatology and Congenital Disorders, Nagoya City University, Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan.

e-mail: yumikoo@med.nagoya-cu.ac.jp