LYST and Chediak-Higashi syndrome: Mutations in the LYST gene located on 1q42.1–42.2, have been identified as a cause of Chediak–Higashi syndrome that is associated with primary HLH,[16] however, some cases who have LYST gene mutations never show any clinical manifestations of Chediak–Higashi syndrome.[17] In the case, genetic testing of the patient and her mother identified a monoallelic mutation in LYST (exon46; c.10526G >A; p.Arg3509Gln) and we also found a heterozygous mutation on the intron of Exon 38 (c.9162 + 11G >A).