Clinical phenotype and molecular basis of factor xi deficiency in turkish population

Factor XI deficiency is a rare coagulation disorder with variable bleeding severity. Its frequency is known to be highest among Ashkenazi Jews. No research study evaluated the characteristics of factor XI-deficient individuals in the Turkish population before. In this study, we report the data, including the results of the genetic analysis of eleven factor XI-deficient cases (five with severe deficiency and six with mild deficiency) registered in the records of Pediatric Hematology Department of Gazi University Medical School and their fifteen family members diagnosed as factor XI-deficient in context of this study. Six of the index cases were diagnosed during evaluation of a prolonged activated partial thromboplastin time ordered as part of routine laboratory examination or pre-operative screening, while the remainders presented with bleeding. All of the fifteen family members affected were unaware of their deficiency before. In this study with eleven index cases, ten different mutations were identified, four of them being novel. Owing to the challenge of its diagnosis, factor XI deficiency is likely to be underdiagnosed in the Turkish population, too. As the rate of consanguineous marriages is high in Turkey, severe deficiency resulting from homozygous mutations may be particularly common. The findings of this study support the genetic heterogeneity of this disorder outside the Jewish population.Keywords: factor XI deficiency, genetic, presenting sign.