Initial clinical studies on cells derived from BTHS patients indicated a defect in remodeling of monolysocardiolipin to mature cardiolipin and an overall decrease in mature cardiolipin content [20,21,22,23,24], suggesting that the primary enzymatic function of Tafazzin is to generate mature cardiolipin within the mitochondria (see Figure 1). This evidence concerns the gene TAFAZZIN and Barth syndrome.