Objective: To investigate the molecular pathogenesis of two coagulation factor XI (FXI) deficiency patients.

Methods: The diagnosis was validated by coagulant assays: APTT and correct test, PT, INR and coagulation factors activities. Coagulation factor activity were tested with clotting assay. The patients' DNA were extracted and all exons and flanking sequences of FXI gene were amplified using PCR. After purified, the products were sent for sequencing directly, the mutations were detected by comparing with wild sequences and analyzed using some bioinformatics software.

Results: The two patients were diagnosed as coagulation factor XI deficiency due to prolonged APTT and low activities of coagulation factor FXI. The results of APTT, FXI:C was 88.1s, 1.1% and 107.1s, 3.8% , respectively. Genetic analysis found that compound heterozygous mutations g.1251-1G > A and g.1271delT in the first patient and the sequencing results of TA plasmid clones showed that the two mutations were located on different single strands of chromosomes. Double heterozygous mutations g.1070A >G and g.1446C > G were detected in the second patient, resulting in Lys357Arg and Cys482Stop. Software analysis indicated the mutations probably brought amino acid sequence changed, protein features affected and splice site changed.

Conclusion: Compound heterozygous mutations g.1251-1G > A, g.1271delT and g.1070A > G , g.1446C > G had been identified in two coagulation factor XI deficiency patients, which might be the cause of their prolonged APTT and low FXI:C. To the best of our knowledge, the four mutations are reported for the first time in the literature.

Disclosures

No relevant conflicts of interest to declare.

Author notes

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Asterisk with author names denotes non-ASH members.

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