A novel mutation that leads to a congenital factor XI deficiency in a Japanese family

We have identified a novel mutation leading to a congenital deficiency of t he coagulation factor XI (FXI) in a Japanese family. A propositus was a 42- year-old female patient without bleeding tendency. Coagulant activity and t he antigen level of FXI in her plasma were below the detectable range. The nucleotide sequences of the FXI gene of this patient were determined by a d irect sequence method established in this study. A novel nonsense mutation (CAA; Gly263 --> TAA; stop) was identified in exon 8 of the FXI gene. Her p arents are first cousins, and a polymerase chain reaction-restriction-fragm ent length polymorphism analysis revealed that her parents were heterozygou s at this nucleotide position. This patient inherited mutant alleles from h er parents and is homozygous at this nucleotide position. The nonsense muta tion in the FXI gene is responsible for her deficiency of FXI. Am. J. Hemat ol. 63:165-169, 2000. (C) 2000 Wiley-Liss, Inc.