As many TAZ mutations result in the production of mutant TAZ proteins with little or no function [16,17,19,20] rather than a complete absence of TAZ protein, we compared the proteome of systemic Taz knockout hearts (TazKO) that completely lack Taz protein [8] with our BTHS patient-specific mouse TazPM♂ model that expresses a stable mutant TazD75H protein. The gene discussed is TAFAZZIN; the disease is Barth syndrome.