Lithuanian haemophilia A and B registry comprising phenotypic and genotypic data

Haemophilia represents the most common hereditary severe bleeding disorder in humans. About 100 families with this condition live in Lithuania, one of the Baltic states with a population of 3.7 million. Haemophilia care and g enetic counselling are still rendered difficult owing to limited availabili ty of clotting factor concentrate and molecular genetic diagnosis. In the p resent study, a haemophilia registry, comprising phenotypic and genotypic d ata of the majority of Lithuanian haemophilia A and B patients, was establi shed. The phenotype includes the degree of severity, factor VIII:C, factor VIII:Ag, factor IX:C, von Willebrand factor and antigen (VWF:RiCoF, vWF:Ag) and inhibitor status. Genotyping of the factor VIII and IX genes was perfo rmed using mutation screening methods and direct sequencing. In 61 out of 6 3 patients with haemophilia A (96.8%) and all eight patients with haemophil ia B (100%), the causative mutations could be detected. Nineteen of the fac tor VIII gene defects and two of the factor IX gene mutations are reported for the first time. Identified mutations allowed direct carrier diagnosis i n 83 female relatives revealing 44 carriers, 38 non-carriers and one somati c mosaicism. The information provided by this registry will be helpful for monitoring the treatment of Lithuanian haemophilia patients and also for re liable genetic counselling of the affected families in the future.