[Factor XI deficiency caused by a mutation of Gly400Val]

The patient described herein is a 69-year-old Japanese woman with a history of excessive bleeding after left heminephrectomy for a malignant renal tumor at 31 years of age. Her parents, who do not have abnormal bleeding, are first cousins. Her factor XI activity was less than 1% of normal with an prolonged activated partial thromboplastin time (APTT) of 74.3 seconds. Analysis of the patient's factor XI genes revealed homozygosity for a valine substituting for the wild-type glycine at amino acid 400 (Gly400Val). The patient has two children, neither of whom has abnormal bleeding and whose factor XI activities are 62% and 57% of normal, with APTT levels within normal limits in both cases. We herein report on a Japanese family with factor XI deficiency caused by Gly400Val mutation.