Analysis of inversions in the factor VIII gene in Spanish hemophilia A patients and families
- Hospital de Sant Pau, Barcelona (Spain)
- Hospital Vall d`Hebron, Barcelona (Spain)
Intron 22 is the largest intron of the factor VIII gene and contains a CpG island from which two additional transcripts originate. One of these transcripts corresponds to the F8A gene which have telomeric extragenic copies in the X chromosome. An inversion involving homologous recombination between the intragenic and the distal or proximal copies of the F8A gene has been recently described as a common cause of severe hemophilia A (HA). We analyzed intron 22 rearrangements in 195 HA patients (123 familial and 72 sporadic cases). According to factor VIII levels, our sample was classified as severe in 114 cases, moderate in 29 cases and mild in 52 cases. An intron 22 (F8A) probe was hybridized to Southern blots of BcII digested DNA obtained from peripheral blood. A clear pattern of altered bands identifies distal or proximal inversions. We detected an abnormal pattern identifying an inversion in 49 (25%) of the analyzed cases. 43% of severe HA patients (49 cases) showed an inversion. As expected, no inversion was found in the moderate and mild group of patients. We found a high proportion (78%) of the distal rearrangement. From 49 identified inversions, 33 were found in familial cases (27%), while the remaining 15 were detected in sporadic patients (22%) in support that this mutational event occurs with a similar frequency in familial or sporadic cases. In addition, we detected a significant tendency of distal inversion to occur more frequently in familial cases than in sporadic cases. Inhibitor development to factor VIII was documented in approximately 1/3 of the patients with inversion. The identification of such a frequent molecular event in severe hemophilia A patients has been applied in our families to carrier and prenatal diagnosis, to determine the origin of the mutation in the sporadic cases and to detect the presence of germinal mosaicism.
- OSTI ID:
- 134199
- Report Number(s):
- CONF-941009-; ISSN 0002-9297; TRN: 95:005313-0935
- Journal Information:
- American Journal of Human Genetics, Vol. 55, Issue Suppl.3; Conference: 44. annual meeting of the American Society of Human Genetics, Montreal (Canada), 18-22 Oct 1994; Other Information: PBD: Sep 1994
- Country of Publication:
- United States
- Language:
- English
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