The following FHL subtypes have been described: FHL-2 due to mutations in PRF1, FHL-3 (UNC13D), FHL-4 (STX11), FHL-5 (STXBP2), Griscelli Syndrome type 2 (RAB27A) and Chediack-Higashi syndrome (LYST) (9–15). The gene discussed is UNC13D; the disease is Griscelli disease.