RESUMEN
Factor XI (FXI)-deficiency is a rare coagulation disorder inherited as an autosomal recessive trait, which is most common in Ashkenazi Jews, but also found in other groups like Moslems. We have reviewed for the first time cases of FXI deficiency in southern Iran in order to analyze their mutations related to factor XI, the main clinical and biological features, levels of circulating factor XI, and bleeding history. All 15 exons and exon-intron boundaries of F11 were polymerase chain reaction amplified using sets of primers designed on the basis of the known genomic sequence of the gene. Among bleeding disorder cases, five were FXI-deficient. FXI clotting activity ranged 0.39-16%. All were severely deficient. In all analyzed patients, functional level of FXI was markedly reduced, confirming the diagnosis of quantitative FXI deficiency. Sequencing of F11 identified three mutations: (1) a highly prevalent type II nonsense mutation (Glu117stop) in a homozygous patient, (2) a previously reported missense (Glu547Lys), and (3) novel missense (Gly372Ala) mutation. No causative mutation was found in the sequenced regions of other patients. One novel mutation and two previously described mutations were identified in patients living in southern Iran. No recurrent mutation was found, perhaps because there is a more intense population mixing in southern Iran. Screening a higher number of FXI-deficient patients will also be necessary to reveal the existence of a founder effect for these mutations in the Iranian population.