STXBP2 and Griscelli disease: Patients were divided into four groups: 1) with PRF1 mutation (n = 46), 2) with UNC13D mutation (n = 38), 3) with STX11/STXBP2 mutation (n = 25) and 4) with Griscelli syndrome type 2/ Chediak–Higashi syndrome (GS2/CHS) diagnosis (n = 44).