The clinical and biochemical phenotypes in COX15 defects are more heterogeneous than in other conditions associated with COX deficiency, such as mutations in SURF1.
Here we show that overexpression of COX15, a protein involved in the synthesis of heme A, the heme prosthetic group for COX, can functionally complement the isolated COX deficiency in fibroblasts from a patient with fatal, infantile hypertrophic cardiomyopathy.