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Biochemical and molecular analysis of an X‐linked case of Leigh syndrome associated with thiamin‐responsive pyruvate dehydrogenase deficiency

1997; Springer Science+Business Media; Volume: 20; Issue: 4 Linguagem: Inglês

10.1023/a

1573-2665

Etsuo Naito, Masayoshi Ito, Ichiro Yokota, Takahiko Saijo, Junko Matsuda, Hitoshi Osaka, Shioko Kimura, Yuichi Kuroda,

Alcoholism and Thiamine Deficiency

Abstract We report molecular analysis of thiamin‐responsive pyruvate dehydrogenase complex (PDHC) deficiency in a patient with an X‐linked form of Leigh syndrome. PDHC activity in cultured lymphoblastoid cells of this patient and his asymptomatic mother were normal in the presence of a high thiamin pyrophosphate (TPP) concentration (0.4 mmol/L). However, in the presence of a low concentration (1 X 10‐4 mmol/L) of TPP, the activity was significantly decreased, indicating that PDHC deficiency in this patient was due to decreased affinity of PDHC for TPP. The patient's older brother also was diagnosed as PDHC deficiency with Leigh syndrome, suggesting that PDHC deficiency in these two brothers was not a de novo mutation. Sequencing of the X‐linked PDHC E1 α subunit revealed a C → G point mutation at nucleotide 787, resulting in a substitution of glycine for arginine 263. Restriction enzyme analysis of the E1α gene revealed that the mother was a heterozygote, indicating that thiamin‐responsive PDHC deficiency associated with Leigh syndrome due to this mutation is transmitted by X‐linked inheritance.