Novel cytochrome B gene mutations causing mitochondrial disease in autism

The recent scientific literature has documented an association between autism and mitochondrial dysfunction, yet the majority of reported cases of individuals with autism and mitochondrial disease have not reported a specific genetic defect to explain the cause of themitochondrial dysfunction. Herewe report two boys with regressive-type autismwith similar biochemical, electron microscopy and electron transport chain abnormalities consistent with a mitochondrial disorder. Both boys manifested rare mutations in evolutionarily conserved regions of the cytochrome b gene, a gene that codes for an important component of complex III- one of the essential electron transport chain complexes. Only one of these mutations has been previously reported, making these mutations novel. Electron transport chain studies in two boys within this report are consistent with dysfunction of the electron transport chain beyond a complex III defect, consistent with other reports describing the effects of cytochrome b gene mutations. This report expands the knowledge of the etiology of mitochondrial dysfunction in children with autism.