[Analysis of a Patient with Severe Hemophilia A Due to a Large Duplication of F8 Gene].

OBJECTIVE:To report on a case with severe hemophilia A (HA) due to a large duplication of F8 gene.METHODS:Inversion detection, Sanger sequencing, and multiplex ligation-dependent probe amplification (MLPA) were used to detect the mutation in the proband and his mother.RESULTS:The patient, a 7-year-old boy, was diagnosed with severe HA at 8 months. No inhibitor was developed over 150 exposure days. Intronic inversion detection and Sanger sequencing have failed to identify pathogenic variants, while MLPA revealed a large duplication [Ex 1_22 dup (2 copies)] in the proband, for which his mother was a carrier [Ex 1_22 dup (3 copies)]. Large duplications of the F8 gene have so far been found in 24 HA patients, all of whom had a severe phenotype, only one had a history of inhibitors.CONCLUSION:Large duplications of F8 gene are associated with severe HA. The diagnostic rate for HA may be increased by MLPA.