Non-Inversion Variants in Sporadic Hemophilia A Rarely Recur.

Hemophilia A (HA), an X-linked bleeding disorder caused by Factor VIII (F8) gene mutations, persists in the population due to sporadic cases arising from de novo mutations. This study analyzed 24 pedigrees from hemophilia registries of multiple medical centers in Taiwan to assess whether sporadic non-inversion variants (NIVs) recur in the same generation within families. Linkage analysis using intragenic and extragenic markers combined with amplification refractory mutation system-quantitative polymerase chain reaction (ARMS-qPCR) revealed that among 16 individuals inheriting the same X chromosome as the one bearing the sporadic HA-causing mutation, none carried the F8 variant. These findings strongly suggest that sporadic NIVs exhibit very low risk of recurrence. Our results provide critical information for recurrence risk assessment and counseling strategies for HA sporadic NIVs.