Cytochrome C Oxidase Assembly Factor 5 (COA5)

A homozygous mutation in C2orf64 is described in two siblings affected by fatal neonatal cardiomyopathy. Pathogenicity of the mutation is supported by the results of a complementation experiment, showing that complex IV activity can be fully restored by retroviral transduction of wild-type C2orf64 in patient-derived fibroblasts. Detailed analysis of complex IV assembly intermediates in patient fibroblasts by 2D-BN PAGE revealed the accumulation of a small assembly intermediate containing subunit COX1 but not the COX2, COX4, or COX5b subunits, indicating that C2orf64 is involved in an early step of the complex IV assembly process.C2orf64 is essential for human complex IV assembly and that C2orf64 mutational analysis should be considered for complex IV deficient patients, in particular those with hypertrophic cardiomyopathy.