HEMOPHILIA B MUTATIONS IN ARGENTINA; A PROTOCOL FOR MOLECULAR ANALYSIS OF THE FACTOR IX GENE.

RADIC P, ROSSETTI L, CANDELA M, LARRIPA I, BIANCO R, DE TEZANOS PINTO M, DE BRASI C.

Vancouver, Canadá.

Congreso; XXVII International Congress of the Word Federation of Hemophilia (WFH).; 2006

Word Federation of Hemophilia (WFH).

Hemophilia B (HB) is an X-chromosome inherited disorder caused by deleterious mutations in the coagulation factor IX gene (F9) that affects approximately 1 in 30000 men worldwide. Free of recurrent DNA inversions, the molecular basis of HB is heterogeneous. The aim of this work is to set up and apply a protocol for F9 analysis and to present the first series of HB associated gene defects in Argentina. Identification of gene structural changes (large deletions) is achieved by standard PCR analysis of the FIX gene (12 amplimers). Screening for small mutations (small Ins/Del and point mutations) is performed by conformation sensitive gel electrophoresis, followed by DNA-sequencing. So far, we have identified FIX gene defects in 8 unrelated HB affected families. All of them were previously reported in the HB mutation database (HBMD): a 4-nucleotide deletion affecting the donor splicing site of IVS1 in a patient with FIX inhibitors, 3 nonsense mutations (2 of them associated with inhibitor development) and 4 missense changes, two leading to severe phenotype, one moderate and one mild; none of them developing inhibitors. Notably, among the group of HB mutations reported here, 2 of them compute more than 50 entries in the HBMD, and accordingly, these represent DNA transitions affecting the hypermutable dinucleotide CpG.   In conclusion, the F9 analysis algorithm applied results accurate and cost-effective, and it will benefit both the genetic counseling of families with HB and the provision of important information for the treatment design.