According to recent human genetics findings, mutations in FECH, ALAS2, and CLPX [174] underlie most cases of the disorder erythropoietic protoporphyria, while mutations in ALAS2 and in the mitochondrial glycine transporter SLC25A38 are the most frequent causes of congenital sideroblastic anemia [175]. Here, SLC25A38 is linked to autosomal recessive sideroblastic anemia.