Detection of Sites of Point Mutations in Some Exons of Factor VIII Gene in Hemophilia A Patients

Hemophilia A is an X linked bleeding disorder caused by factor VIII deficiency. FVIII gene is located on the long arm of X chromosome at Xq28 spans 186kb and consists of 26 exons. The main objective of this study was to find out the pattern of mutations in the Factor VIII gene that causes hemophilia A in Egyptian population and to help in proper understanding of the molecular basis of hemophilia A disease thus providing a better chance for accurate carrier detection and prenatal diagnosis. For factor VIII gene mutations, we focused on six coding regions (exons 2, 8, 18, 22, 23 and 24). The reason for studying these exons was their smaller sizes and high mutational rates. The DNA from 24 unrelated hemophilia A patients was analyzed by means of Polymerase Chain Reaction (PCR) followed by Single Standard Conformational Polymorphisms (SSCP) and finally DNA sequencing for cases with abnormal patterns by SSCP Ten healthy volunteers were included as control group. In present work, the mutation detection rate was 1/24 or 4% among the studied groups. A missense mutation (Thr 49 Ala) was detected in exon 2 of patient number 8 which revealed substitution of single base (A) by (G) at codon 49, leading to change of that codon from therionine amino acid to alanin amino acid. We could not detect any mutation in the remaining 23 patients in either of five exons 8, 18, 22, 23 and 24 which suggests that mutations in these coding regions of factor VIII are uncommon in hemophiliac patients from Egypt. Our data indicate ethnic diversity when compared with other world populations and therefore calls for a detailed study into the molecular basis of classical hemophilia A in Egypt on larger group of patients to help in accurate carrier detection and prenatal diagnosis.