Intron 22 factor VIII gene inversions in Argentine families with severe haemophilia A

Intron 22 factor VIII gene inversion (Inv22) is the most common mutation ca using severe haemophilia A (SHA). We studied Inv22 in 34 SHA affected famil ies by Southern blotting. Data from the familial history of the disease and the inhibitor status were also included. We found Inv22 in 41 % of SHA Arg entine families (35 % with type 1 and 6 % with type 2), in close agreement with previously reported series. No significant correlation between the inh eritance (familiar or sporadic disease) and the presence of inversions was found. Our population showed 24% of families included at least one hemophil iac with inhibitor. In families positive for Inv22, 29 % of patients develo ped inhibitor but this increased frequency was not statistically significan t. In conclusion, analysis of Inv22 in SHA patients should be used as a fir st line method because it provides useful and secure information for carrie r detection and prenatal diagnosis in a high percentage of cases.