Leigh syndrome caused by mutations in the flavoprotein (Fp) subunit of succinate dehydrogenase (SDHA)

Detailed clinical, neuroradiological, histological, biochemical,
and genetic investigations were undertaken in a child suffering
from Leigh syndrome. The clinical symptoms started at age five
months and led to a severe progressive neurodegenerative disorder
causing epilepsy, psychomotor retardation, and tetraspasticity.
Biochemical measurement of skeletal muscle showed a severe decrease
in mitochondrial complex II. Sequencing of SDHA revealed compound
heterozygosity for a nonsense mutation in exon 4 (W119X) and a
missense mutation in exon 3 (A83V), both absent in normal controls.
In six additional patients---five with Leigh or Leigh-like syndrome
and one with neuropathy and ataxia associated with isolated
deficiency of complex II---mutations in SDHA were not detected,
indicating genetic heterogeneity.