A Dose of Haematology News #2.4.1 - Why More Black American Haemophiliacs Have Inhibitors?

I read an interesting article in the NEJM this morning. It was a study to try to explain why black population in America with Haemophilia A (FVIII deficiency) more readily forms antibody against the transfused factor VIII used as part of treatment compared to their white counterpart.

The suggested answer put forward by the team from America was surprisingly elegant and simple. There are 6 types of (wild) type, or naturally occurring FVIII in humans, conveniently named H1 to H6. Whites and majority of other races only have gene for either H1 or H2 (or deficiency of H1 or H2 in case of Haemophilia). In this study of 78 Black subjects, the haplotype of the FVIII gene was mapped and it was found that 24% of them have eitehr H3 or H4 haplotypes. Since the commercially available FVIII replacement are made from H1 and H2, those that are natively non-H1 or H2 will understandably produce antibodies against them.

In this study, the statistical analysis just about found significance at p=0.04, OR 3.6 (1.1 to 12.3). Maybe if bigger subject population was studied, the power of the study will be higher. Maybe we should do a similar study here in Malaysia to at least map the wild-type gene that our Haemophiliacs carry.