Combined hereditary factor XI (plasma thromboplastin antecedent) deficiency, von Willebrand's disease, and xeroderma pigmentosum in a Japanese family.

We report a 28-year-old-Japanese male who had a skin tumor derived from variant type xeroderma pigmentosum (XP), combined with factor XI (FXI) deficiency and type IIB von Willebrand's disease (vWd). The patient had abnormal bleeding history on tooth extraction. FXI clotting activity (FXI:C) and antigen (FXI:Ag) were remarkably decreased (< 0.01 U/ml, < 0.02 U/ml, respectively). Factor VIII (FVIII) clotting activity, von Willebrand factor antigen (vWf:Ag), and ristocetin cofactor (RCoF) were 0.43 U/ml, 45%, and 57%, respectively. Ristocetin-induced platelet agglutination (RIPA) revealed hyper-aggregation compared with a normal control. Multimeric composition of vWf in plasma showed a reduction in high molecular weight forms. The family study revealed two other subjects with homozygous hereditary FXI deficiency and vWd, and five subjects with heterozygous FXI deficiency. The relationship between FXI deficiency and vWd is discussed and previously reported cases are reviewed.