title: Frequency of intron 1 and 22 inversions of Factor VIII gene in Mexican patients with severe hemophilia A.
abstract: Hemophilia A (HA) is one of the most common inherited bleeding disorders caused by FVIII gene mutations. Inversion of intron 22 (inv22) originates 50% of cases of severe HA and is a major risk factor for inhibitor development. Inversion of intron 1 (inv1) has been reported to occur in 2-3% of severe HA patients. We studied both inversions to determine their frequencies in Mexican patients with severe HA and to compare these data with other HA populations. The inv22 was evaluated as a risk factor for FVIII inhibitor development in severe HA patients. We studied 44 patients from 31 severe HA families for the detection of inv22 and 94 patients from 65 families to detect inv1. We used the subcycling long-distance PCR to detect inv22 and rapid PCR in duplex reactions to detect inv1. We found a frequency of 45% for the inv22 and no inv1-positive patients (0%). These frequencies were not statistically different from other populations, although haplotype analyses of FVIII gene and telomeric regions should be incorporated to explore population-specific variation of inv1 frequencies. Inv22-positive patients showed 1.88X higher risk for developing inhibitors with respect to patients carrying other severe mutations; however, this OR value was not significant. Our findings confirm inv22 as a hot-spot for severe HA and evidence the low frequency of inv1 in a Mexican population. The non-significant risk for developing inhibitors among inv22-positive patients agrees with the variety of genetic and non-genetic factors involved in such a complication.
authors.affiliation: División de Genética, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social (IMSS), Guadalajara, Jalisco, México.
authors.forename: Johanna Milena
authors.initials: JM
authors.lastname: Mantilla-Capacho
authors.forename: Claudia Patricia
authors.initials: CP
authors.lastname: Beltrán-Miranda
authors.forename: Hilda
authors.initials: H
authors.lastname: Luna-Záizar
authors.forename: Lilia
authors.initials: L
authors.lastname: Aguilar-López
authors.forename: María Amparo
authors.initials: MA
authors.lastname: Esparza-Flores
authors.forename: Beatriz
authors.initials: B
authors.lastname: López-Guido
authors.forename: Rogelio
authors.initials: R
authors.lastname: Troyo-Sanromán
authors.forename: Ana Rebeca
authors.initials: AR
authors.lastname: Jaloma-Cruz
mesh_terms: D007446:Chromosome Inversion / Q000235:genetics* / Q000706:statistics & numerical data; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005169:Factor VIII / Q000235:genetics* / Q000276:immunology; D005787:Gene Frequency; D006467:Hemophilia A / Q000235:genetics* / Q000628:therapy; D006801:Humans; D007438:Introns / Q000235:genetics*; D007518:Isoantibodies / Q000009:adverse effects* / Q000276:immunology; D008800:Mexico; D016017:Odds Ratio
chemical_list: D007518:Isoantibodies; D005169:Factor VIII