Barel et al. (2008) reported a large consanguineous Israeli Bedouin kindred in which 25 individuals had an autosomal recessive syndrome comprising severe psychomotor retardation and extrapyramidal signs. Affected individuals seemed normal at birth without any dysmorphic features, but ... Barel et al. (2008) reported a large consanguineous Israeli Bedouin kindred in which 25 individuals had an autosomal recessive syndrome comprising severe psychomotor retardation and extrapyramidal signs. Affected individuals seemed normal at birth without any dysmorphic features, but showed developmental delay in the first few months of life. Neurologic features included dystonia, athetoid movements, ataxia, mild axial hypotonia, increased tone, hyperreflexia, and inability to walk unsupported. Other features included restlessness, marked global dementia, severe defects in verbal receptive communication, and near total absence of expressive communication skills, with inability to express any words at any age. The phenotype was not lethal, with some affected individuals surviving well into their thirties. Brain MRI in 5 patients showed bilateral symmetric abnormal findings in the basal ganglia. Serum lactate was mildly elevated and muscle biopsies showed a reduction in mitochondrial complex III activity.
In affected members of a large Israeli Bedouin kindred with complex III deficiency, Barel et al. (2008) identified a homozygous mutation in the UQCRQ gene (612080.0001).