Background: : Inherited deficiency of clotting factor XI (FXI) is a rare autosomal disorder caused by defects in the F11 gene. The F11 gene is located on the long arm of chromosome 4 (4q35), and consists of 15 exons. Up to now, over 220 mutations in F11 gene have been described in patients with FXI deficiency.

Aims: The aim of this study is to present the genetic analysis results of patients who were diagnosed as severe or mild Factor XI deficiency in northern region of Turkey.

Methods: Factor VIII, IX, XII and VWF deficiency were investigated in patients who were examined for prolonged APTT. Factor XI deficiency has been demonstrated. Families were informed about the genetic transition and screened. Approval was obtained from the ethics committee of our hospital. Genomic DNA was isolated from peripheral blood core cells. Targeted gene region was amplified by PCR. Libraries covering genes were prepared according to the Nextera XT DNA Library Prep protocol and sequenced in Illumina MiSeQ system.

Results: Mutation has been detected in all patients. Five patients were homozygous, one patient was compound heterozygous, and 23 patients were heterozygous. Thirty-five mutant alleles were detected in a total of 29 patients. Sixteen of the patients were male and thirteen were female. p.Ala109Thr was found in 71% (25/35) of the mutated alleles. p.Ala43Thr was found in 17% (6/35) of the mutated alleles. p.Glu135Ter was found in 6% (2/35) of the mutated alleles. c.325+1G˃A was found in 6% (2/35) of the mutated alleles.

Conclusions: We report here four different mutations in 10 families with FXI deficiency. The few paper reported previously from Turkey, indicate the genetic heterogeneity of FXI deficiency in the Turkish population. But in this study, p.Ala109Thr was found with high frequency in northern region of Turkey.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/fxi-gene-mations-in-northern-region-of-turkey/