Further mutations in TRNT1 have been reported in patients with a combination of abnormal blood cells (sideroblastic anemia, B lymphocyte or combined B and T immunodeficiency), metabolic crisis, and multisystem mitochondrial disease (retinitis pigmentosa, hepatosplenomegaly, exocrine pancreatic insufficiency, and renal tubulopathy [62,63–65]. This evidence concerns the gene TRNT1 and immunodeficiency disease.