1. Saccharopinuria accompanied by hyperammonemia and hypercitrullinemia presented with elderly-onset epilepsy, progressive cognitive decline, and gait ataxia
- Author
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Masahide Yazaki, Ryusei Nishigori, Yasuyuki Takai, Akihiro Kawata, Toshihiro Ohura, Shinsuke Tobisawa, Tomiko Kuhara, Ryohei Norioka, Asuka Funai, Kazushi Takahashi, Masayoshi Nagao, and Kazuhito Miyamoto
- Subjects
0301 basic medicine ,medicine.medical_specialty ,Argininosuccinate synthase ,Case Report ,030105 genetics & heredity ,Gene mutation ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Internal medicine ,medicine ,biology ,business.industry ,Citrullinemia ,Hyperammonemia ,General Medicine ,Ornithine ,medicine.disease ,Endocrinology ,Citrin ,chemistry ,Saccharopine ,Saccharopinuria ,biology.protein ,business ,030217 neurology & neurosurgery - Abstract
We report a case of saccharopinuria with hyperammonemia and hypercitrullinemia in a Japanese woman who presented with elderly-onset epilepsy, progressive cognitive decline, and gait ataxia. Blood amino acid analysis revealed an increase in citrulline, cystine, and lysine levels, and urine amino acid analysis showed increased citrulline and cystine levels. Urine metabolomics revealed an increased saccharopine level, leading to the definitive diagnosis of saccharopinuria. In western blots of liver biopsy samples, normal citrin levels were observed, suggesting that adult-onset citrullinemia type 2 (CTLN2) was not present. In addition, decreased argininosuccinate synthetase (ASS) levels were observed, and ASS1 gene, a causative gene for citrullinemia type 1 (CTLN1), was analyzed, but no gene mutations were found. Because the causes of hypercitrullinemia were not clear, it might be secondary to saccharopinuria. Muscle biopsy findings of the biceps brachii revealed diminished cytochrome c oxidase (COX) activity, mitochondrial abnormalities on electron microscopy and p62- positive structures in immunohistochemical analyses. Saccharopinuria is generally considered a benign metabolic variant, but our case showed elevated lysine and saccharopine levels causing ornithine circuit damage, mitochondrial dysfunction, and autophagy disorders. This may lead to so far unknown neurological disorders.
- Published
- 2021