SURF1 gene mutations cause a severe COX deficiency manifesting as the Leigh syndrome in humans, whereas in mice SURF1(-/-) knockout leads only to a mild COX defect.
The loss of the wild-type COX8A protein severely impairs the stability of the entire cytochrome c oxidase enzyme complex and manifests in isolated complex IV deficiency in skeletal muscle and fibroblasts, similar to the frequent c.845_846delCT mutation in the assembly factor SURF1 gene.
It usually presents in infancy and is genetically heterogeneous, but most individuals with mitochondrial complex IV (or cytochrome c oxidase) deficiency have mutations in the biogenesis factor SURF1.
Mutations in the nuclear SURF-1 gene lead directly to cytochrome-c oxidase deficiency, the most common respiratory chain defect in Leigh syndrome, a neurodegenerative mitochondrial disease involving the deep gray matter and brain stem.
Marked prevalence of two nuclear DNA mutations (845-846delCT in the SURF1 gene and 1541G>A in the SCO2 gene) associated with COX deficiency in a Slavonic population suggests the existence of regional differences in the genetic basis of COX deficiency.
We describe a patient with Leigh syndrome harbouring a mutation in SURF1 who was reported decades ago with a tissue-specific cytochrome c oxidase deficiency.
Mutations in Surf1, a human gene involved in the assembly of cytochrome c oxidase (COX), cause Leigh syndrome, the most common infantile mitochondrial encephalopathy, characterized by a specific COX deficiency.
These data confirm that the spectrum of MRI findings in LS is variable and that SURF1 mutations should be considered in patients with encephalomyopathy and COX deficiency even when early MRI findings are negative.
The authors have identified four pathogenic mutations including a novel, in-frame, 15-bp tandem duplication (806-820) in exon 8 and a novel 751+1G>A splice site mutation in SURF1 in three cases of LS with COX deficiency.
We conclude that, although mtDNA mutations are considered to be rare in LS with COX deficiency, the T 5537i mutation should be screened for in cases of LS with COX deficiency when SURF1 gene mutations have been excluded, especially when complex I activity is also decreased.
The authors have identified four pathogenic mutations including a novel, in-frame, 15-bp tandem duplication (806-820) in exon 8 and a novel 751+1G>A splice site mutation in SURF1 in three cases of LS with COX deficiency.