Molecular detection or carriers of hemophilia A in Mexican families.

The genomic DNAs of carrier mothers from 20 hemophilia A unrelated Mexican families were analysed by polymerase chain reaction (PCR) amplification of the Bcl I polymorphic region at intron 18 of the factor VIII gene. Eleven women (55%) were found to be informative (Bcl I+/Bcl I-), eight (40%) were Bcl I- homozygotes and one (5%) was a Bcl I+ homozygote. In 18 daughters of the informative families we were able to establish carrier status for eight. The frequency of the Bcl I alleles in the 20 mothers was 0.675 for Bcl I- and 0.325 for Bcl I+ which give a frequency of 44% of heterozygous females in our sample.