Developmental delay is indicated in 3MC syndrome, LAD type 2, Cohen syndrome, Kabuki syndrome, Barth syndrome, P14 deficiency, adenosine deaminase acting on RNA 1 (ADAR1) deficiency, HIES with PGM3 mutations, PNP deficiency, MKD, DGS, NBS, and ITCH deficiency.1, 10, 32. The gene discussed is PGM3; the disease is Barth syndrome.