A family with pyruvate dehydrogenase complex deficiency due to a novel C>T substitution at nucleotide position 407 in exon 4 of the X-linked Epsilon1alpha gene.
The pyruvate dehydrogenase complex (PDHc; McKusick 312170), localised in the mitochondrial matrix, is a multienzyme complex which converts pyruvate to acetyl-CoA. A deficiency of PDHc leads to inadequate removal of pyruvate and lactate resulting in lactic acidaemia and insufficient energy production. The major cause of PDHc deficiency is a defect in the E1alpha component. The gene of this component is localised to Xp22.1. We describe two brothers with a relatively mild clinical phenotype of PDHc deficiency. Onset of disease was associated with muscle weakness and swallowing difficulties in both. At follow-up, the older brother developed encephalopathic features consistent with Leigh syndrome. Lactate to pyruvate ratios were low, consistent with a PDHc deficiency which was confirmed by measurements of PDHc activity in thrombocytes. A 407C>T change in exon 4 of the E1alpha gene was found in both brothers and their mother. This substitution predicts a replacement of a conserved alanine at position 136 by valine.


CONCLUSIONS
Due to the X-linked inheritance pattern combined with the overall results of clinical investigations, molecular genetic findings and a corresponding functional deficiency of the gene product we believe that this substitution in the pyruvate dehydrogenase E1alpha gene is a mutation leading to pyruvate dehydrogenase complex deficiency in this family.
Tulinius
Már
M
Department of Paediatrics, Sahlgrenska University Hospital/Ostra, 41685 Göteborg, Sweden. mar.tulinius@vgregion.se
Darin
Niklas
N
Wiklund
Lars-Martin
LM
Holmberg
Eva
E
Eriksson
Jan Erik
JE
Lissens
Willy
W
De Meirleir
Linda
L
Holme
Elisabeth
E
D019943:Amino Acid Substitution; D001921:Brain / Q000473:pathology; D002331:Carnitine / Q000097:blood; D002675:Child, Preschool; D005091:Exons; D006801:Humans; D007223:Infant; D019344:Lactic Acid / Q000097:blood; D007888:Leigh Disease / Q000235:genetics; D008279:Magnetic Resonance Imaging; D008297:Male; D009154:Mutation; D030481:Pyruvate Dehydrogenase (Lipoamide) / Q000235:genetics*; D015325:Pyruvate Dehydrogenase Complex Deficiency Disease / Q000235:genetics*; D019289:Pyruvic Acid / Q000097:blood; D035781:Siblings
D019344:Lactic Acid; D019289:Pyruvic Acid; D030481:Pyruvate Dehydrogenase (Lipoamide); C065640:pyruvate dehydrogenase E1alpha subunit; D002331:Carnitine