Table 2 lists the most common male BTHS patient phenotypes and their possible in utero and perinatal developmental origins. Although female carriers of TAZ mutations are usually asymptomatic and typically undergo selective inactivation of X chromosomes carrying the mutant allele, a couple of reports have shown that affected TAZ female carriers with both abnormal and normal karyotypes can exist [66,67,68]. This presumably occurs due to random X inactivation in utero leading to a high percentage of cells silencing the wildtype allele [69]. The gene discussed is TAFAZZIN; the disease is Barth syndrome.