New Missense Mutation His2026Arg in the Factor VIII Gene Was Revealed in Two Female Patients with Clinical Manifestation of Hemophilia A

Hemophilia A is a recessive X-linked hereditary disease, so its manifestation in women is extremely rare and can be a result of an asymmetric X-chromosome inactivation or, even more rarely, of a presence of mutations in both FVIII gene alleles. We conducted a mutation screening of the FVIII gene in two female patients with clinical hemophilia A manifestation in this study. One patient had a hereditary disease; the second one was diagnosed with acquired hemophilia A as an adult. Both patients carried the same missense mutation His2026Arg. The patient with the hereditary form of the disease also had previously known microinsertion c.4379_4380 insA (p.Asn1460Lys-fs*1). We found no additional aberrations by sequencing of all functionally significant parts of the factor VIII gene of the patient with acquired hemophilia but showed clear asymmetric inactivation of X-chromosomes. Therefore, one of the possible explanations for the emergence of the hemophilic syndrome in this case can be the delayed manifestation of the FVIII gene germline mutation owing to the enhancement of hematopoiesis clonality with age.