Genetic variant detection in a South African haemophilia B population

• Published in: Haemophilia : the official journal of the World Federation of Hemophilia 2024-05, Vol.30 (3), p.765-773
• Main Authors: Bester, Chené, Kloppers, Jean F, van Rensburg, Walter J Janse
• Format: Article
• Language: English
• Subjects: Coagulation factors; Developing countries; Factor IX deficiency; FIX gene; Genetic analysis; Genetic diversity; Genetic screening; Hemophilia; LDCs
• ISSN: 1351-8216; 1365-2516
• DOI: 10.1111/hae.14978

Haemophilia B is characterised by a deficiency of factor IX (FIX) protein due to genetic variants in the FIX gene (F9). Genetic testing may have a vital role in effectively managing haemophilia B. However, in many developing countries, comprehensive genetic variant detection is unavailable. This study aimed to address the lack of genetic data in our country by conducting genetic variant detection on people affected by haemophilia B in our region. Twenty-one participants were screened with a direct Sanger sequencing method to identify variants in the F9 gene. The identified variants were then compared to previously published variants and/or to a reference database. A total of ten F9 genetic changes were detected, with five of them being novel. These identified variants were distributed across different domains of the FIX protein. Only one participant had a history of inhibitor formation against FIX replacement therapy. Notably, this participant had two distinct genetic changes present adjacent to each other. Thus, we hypothesise that the presence of multiple variants within the same functional region of the gene may increase the risk for inhibitor development. The discovery of novel pathogenic variations in the F9 gene highlights the importance of genetic analysis in specific geographical regions. The possible link between a complex variant and inhibitor formation illustrates the potential role that genetic screening has as a pre-treatment tool in predicting treatment reactions and outcomes.