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Biochim Biophys Acta. 2002 Oct 9;1588(1):79-84.

Thiamine-responsive pyruvate dehydrogenase deficiency in two patients caused by a point mutation (F205L and L216F) within the thiamine pyrophosphate binding region.

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  • 1Department of Pediatrics, School of Medicine, University of Tokushima, Kuramoto Cho 3, Tokushima, Japan. enaito@clin.med.tokushima-u.ac.jp

Abstract

The human pyruvate dehydrogenase complex (PDHC) catalyzes the thiamine-dependent decarboxylation of pyruvate. Thiamine treatment is very effective for some patients with PDHC deficiency. Among these patients, five mutations of the pyruvate dehydrogenase (E1)alpha subunit have been reported previously: H44R, R88S, G89S, R263G, and V389fs. All five mutations are in a region outside the thiamine pyrophosphate (TPP)-binding region of the E1alpha subunit. We report the biochemical and molecular analysis of two patients with clinically thiamine-responsive lactic acidemia. The PDHC activity was assayed using two different concentrations of TPP. These two patients displayed very low PDHC activity in the presence of a low (1 x 10(-4) mM) TPP concentration, but their PDHC activity significantly increased at a high (0.4 mM) TPP concentration. Therefore, the PDHC deficiency in these two patients was due to a decreased affinity of PDHC for TPP. Treatment of both patients with thiamine resulted in a reduction in the serum lactate concentration and clinical improvement, suggesting that these two patients have a thiamine-responsive PDHC deficiency. The DNA sequence of these two male patients' X-linked E1alpha subunit revealed a point mutation (F205L and L216F) within the TPP-binding region in exon 7.

PMID:
12379317
[PubMed - indexed for MEDLINE]
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