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Biochemical and molecular analysis of an X‐linked case of Leigh syndrome associated with thiamin‐responsive pyruvate dehydrogenase deficiency
Author(s) -
Naito E.,
Ito M.,
Yokota I.,
Saijo T.,
Matsuda J.,
Osaka H.,
Kimura S.,
Kuroda Y.
Publication year - 1997
Publication title -
journal of inherited metabolic disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 102
eISSN - 1573-2665
pISSN - 0141-8955
DOI - 10.1023/a:1005305614374
Subject(s) - pyruvate dehydrogenase complex , leigh disease , thiamine pyrophosphate , mutation , compound heterozygosity , point mutation , biology , medicine , microbiology and biotechnology , genetics , gene , biochemistry , enzyme , cofactor
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.