Inherited factor XI deficiency is an injuryrelated bleeding disorder that is rare in most populations except for Jews, in whom 2 mutations, a stop mutation in exon 5 (type II) and a missense mutation in exon 9 (type III), predominate. Recently, a cluster of 39 factor XI-deficient patients was described in the Basque population of Southwestern France. In this study, we determined the molecular basis of factor XI deficiency in 16 patients belonging to 12 unrelated families of French Basque

We report on 3 female patients with immunologic thrombocytopenic purpura (ITP) for whom diagnostic procedures evidenced a chronic Hepatitis C virus (HCV) infection. In 2 cases, a transfusion performed more than 10 years ago represented the probable way of contamination. One patient received a course of steroids, which normalized the platelet counts. Another one has been treated with repeated IV immunoglobulins, which induced partial responses of variable duration. HCV is responsible for many autoimmune manifestations and a search for this virus seems warranted for exploring patients with ITP.

Summary. The diagnosis of type I von Willebrand disease (VWD) is not straightforward because of the absence of a single clear-cut biological criteria and the interference of several acquired conditions on phenotype expression. We illustrate here this challenge with the French Basque population characterised by a marked high frequency in both blood group O and factor XI deficiency. From this example one may question the validity of epidemiological studies reporting on VWD prevalence.

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