BTHS (3-methylglutaconic aciduria type II, MIM 300394) is a rare X-linked disorder with an estimated prevalence of 1/300,000–400,000 live births characterized by cardiomyopathy, neutropenia, growth abnormalities, and skeletal myopathy, among other features [1]. The gene discussed is TAFAZZIN; the disease is Skeletal myopathy.