Barth syndrome (BTHS, OMIM #302060) is a mitochondrial disorder caused by loss-of-function mutations involving the TAFAZZIN gene (TAZ, OMIM *300394) on chromosome Xq28 [1]. The disease is transmitted in an X-linked recessive fashion; however, de novo mutations contribute to 13 % of male patients [2]. The main clinical features include cardiomyopathy, intermittent neutropenia, skeletal myopathy, growth delay, distinctive facial gestalt, and organic aciduria [2]. Affected males show complete penetrance with variable expressivity [1]. Seventy percent of patients present with cardiomyopathy in the first year of life and 12 % underwent cardiac transplantation [3]. Cardiomyopathy is the primary determinant of the clinical outcome [4].

The objectives of this manuscript are documenting a novel pathogenic variant of the TAFAZZIN gene, providing a review focusing primarily on the pathological cardiac features in BTHS, and reporting our clinical experience with Elamipretide.