Congenital Factor XI deficiency in an elderly Japanese male accompanied by nonsense mutation p.Trp519* and novel missense mutation p.Ile618Phe

抄録

Objective:In the present study, we identified a genetic mutation in a patient with asymptomatic congenital Factor XI (FXI) deficiency, with an FXI activity of <1%. The mutation was accidentally discovered when the patient was 80 years old. Methods:We performed genome sequencing (GS) on using a whole blood sample from the patient. The nucleotide sequences obtained were compared to the FXI reference GS and mutations were assessed using BioEdit. Results:Notably, exon 14 was not amplified;therefore, all other exons were analyzed. Four heterozygous nucleotide mutations were noted:c.1556G>A, c.1812G>T, c.1839G>A, and c.1852A>T;c.1556G>A and c.1852A>T were associated with amino acid substitutions p.Trp519* and p. Ile618Phe, respectively. Some cases of the amino acid substitution p.Trp519* have been registered in the database;however, to the best of our knowledge, p.Ile618Phe was likely discovered for the first time in this study. Conclusion:Because both gene mutations were heterozygous, the patient had compound heterozygous mutations that decreased FXI activity. J. Med. Invest. 73 : 281-285, February, 2026