Hemophilia A (HA) is an X-linked recessive disorder that results from mutations in the factor VIII gene (FVIII). Most affected patients are males due to the inheritance of mutations in the FVIII gene from their mothers. Females are mostly found to be carriers unless they inherited the mutation from both parents. Obligate carriers of HA are mothers whose sons are affected with HA, or daughters who inherit the mutation from their affected fathers. A possible carrier of HA could be any female who has one or more affected relatives with HA in her family. Hemophilia A carriers (HACs) could present with similar symptoms to affected patients, including low factor VIII level, and risk of bleeding especially after surgical procedures or postpartum hemorrhage.
Objectives: Assessing the phenotype of possible HAC and its association with genetic variants in the FVIII gene for better screening methods for HAC.
Methods: From the period between 25 June and 25 October 2021, the study was conducted at King Abdulaziz University Hospital in Jeddah, Saudi Arabia. We recruited seven mothers whose sons were affected with HA, and 18 possible HAC who are relatives to sever affected patients with HA. All 25 candidates were assessed for the FVIII level, activated partial thromboplastin time (APTT), and bleeding risk and sequenced a part of Exon14 in their FVIII gene.
Results: Twenty-five percent of the participants show a low level of FVIII, however, none of them have prolonged bleeding nor suffer from bleeding tendency. We also identified two missense variants in six of the candidates, but the clinical significance of these variants has not been determined previously.
Conclusion: This pilot study is the first to explore the phenotype of several HAC in Saudi Arabia. A larger scale study with more HA patients and their female relatives is needed to understand the correlation between phenotype and genotype for better screening for HAC.
Keywords: aptt; exon 14; factor viii; female carriers; hemophilia.
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