Spectrum of factor VIII mutations in Arab patients with severe haemophilia A

Haemophilia A is an X-linked recessive bleeding disorder caused by mutations in the factor VIII (FVIII) gene. The mutation spectrum is known in various populations, but not in Arabs. We selected 20 unrelated Arab patients with severe haemophilia A. Those patients underwent detailed clinical examination and their plasma FVIII:C activity was also measured. We extracted DNA from their blood samples and we looked for intron 22 inversion, deletions, insertions and base substitutions in the FVIII gene. Intron 22 inversion was common (detected in 11 patients, 55%), eight base substitutions (six of which are novel) were detected in nine patients (45%) and none had an insertion or deletion. Of eight base substitutions detected, six were potentially pathologic and this was correlated well with the severe clinical phenotype observed. Larger studies with more Arab patients from various Arab countries are needed in order to establish a solid conclusion about the prevalence of various mutations in this unique ethnic group. For the families included in this study, the results obtained can be helpful for carrier testing, prenatal diagnosis or pre-implantation techniques for detection of unaffected embryos.