Combined deficiencies of the pyruvate dehydrogenase complex and enzymes of the respiratory chain in mitochondrial myopathies.
In six patients with mitochondrial (encephalo-) myopathy investigations of skeletal muscle revealed a defect of pyruvate dehydrogenase complex (PDHC) in combination with one or more respiratory chain complex deficiencies. A combination of defects of this kind has not been reported previously. Five of the six patients presented within the 1st year of life and had a severe clinical course. Intrafamilial variability of the clinical course in dizygotic twins both suffering from a cytochrome c oxidase deficiency and one of them also from a PDHC deficiency suggests an additional effect of PDHC deficiency on the clinical symptoms. Immunoblot studies of PDHC in five of the patients revealed no abnormalities in their subunit pattern, rendering a defect of mitochondrial protein import or assembly unlikely. The finding of a combined PDHC and respiratory chain deficiency has implications for the diagnostic approach, for therapy and genetic counselling. The exact pathogenetic mechanism of this combination of defects remains to be elucidated.
Sperl
W
W
Department of Paediatrics, University Hospital of Nijmegen, The Netherlands.
Ruitenbeek
W
W
Sengers
R C
RC
Trijbels
J M
JM
Bentlage
H
H
Wraith
J E
JE
Heilmann
C
C
Stöckler
S
S
Binder
C
C
Korenke
G C
GC
D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008931:Mitochondria, Muscle / Q000201:enzymology* / Q000378:metabolism; D009132:Muscles / Q000201:enzymology*; D009135:Muscular Diseases / Q000201:enzymology* / Q000378:metabolism; D015325:Pyruvate Dehydrogenase Complex Deficiency Disease