In the Kurdish family in which they mapped the FHL4 locus, Zur Stadt et al. (2005) identified a 5-bp deletion in the syntaxin-11 gene (STX11; 605014). The syntaxin 11 protein was absent in the mononuclear cell fraction of ... In the Kurdish family in which they mapped the FHL4 locus, Zur Stadt et al. (2005) identified a 5-bp deletion in the syntaxin-11 gene (STX11; 605014). The syntaxin 11 protein was absent in the mononuclear cell fraction of patients with the deletion (605014.0001). Two additional consanguineous Turkish/Kurdish FHL kindreds harbored the same mutation, while 1 family displayed a large 19.2-kb genomic deletion spanning the entire coding region (exon 2) of STX11 (605014.0002), and 2 families exhibited a nonsense mutation leading to a premature stop codon in the C-terminal end of the protein (Q268X; 605014.0003). As both STX11 and UNC13D (608897) are involved in vesicle trafficking and membrane fusion, the authors concluded that, besides mutations in perforin-1 (170280), defects in the endocytotic or the exocytotic pathway may be a common mechanism in FHL. In a mutation analysis in a group of 63 unrelated patients with FHL of different geographic origins, Zur Stadt et al. (2006) found 6 mutations in the STX11 gene, all in patients of Kurdish origin. Rudd et al. (2006) analyzed the STX11 gene in 34 patients with FHL from 28 unrelated families in whom PRF1 (170280) mutations had been excluded. They identified homozygosity for the 5-bp deletion in 2 brothers previously reported by Zur Stadt et al. (2005) and in an unrelated brother and sister. They identified homozygosity for the Q268X mutation in a Turkish girl previously reported by Zur Stadt et al. (2005) and in a unrelated Turkish boy. Three of the children experienced more than 1 year in remission without specific treatment, which the authors stated was very uncommon in this disease. Two of the children developed severe psychomotor retardation; and 1 developed acute myelodysplastic syndrome, and another, acute myelogenous leukemia. Rudd et al. (2006) suggested that STX11 mutations may be associated with secondary malignancies and noted that 13 individuals from 8 Turkish families had been shown to carry STX11 mutations to that date.