Several DNA probes have been isolated to detect Factor VIII gene and a DNA segment which locates veryclose to the gene.
They have been successfully used to detect carriers and patients of hemophilia A.We analyzed DNA samples of Japanese population to see whether these probesare also useful for carrier detection of hemophilia A in affected Japanese families, since the size and frequency of allelic fragments detected by a DNA probe are sometimes different in various ethnic groups.A probe of St14 (DXS52) is thought to be one of the best probes for such analysis in Caucasian population because it detects very polymorphic DNA fragments containing a minisatellite. When Taq I digests of Japanese DNA samples were hybridized with Stl4, several DNA fragments with a range from 1.7 kb to 5-5 kb were detected, where .at least 6 fragments were polymorphic. A notable difference between Japanese and Caucasian was that a band of 5-5 kb was variable in Japanese while it was constant in Caucasian. We have so far detected 10 alleles, and about 60% of Japanese women were heterozygous. Using these informationsabout Japanese population, we could detect carriers in several families. Other RFLPs data are necessary to increase information content. Similar studies arein progress using different probes i.e. an extragenic probe ; DX13/Bgl II, and two intragenic probes ; exon 14-26/Bcl I and exon 26/Bgl I. We thank Mandel J.L., Strasbourg, Davies K., Oxford and Genetics Institute, Cambridge for probes.
Factor VIII gene rearrangement in hemophilia A carrier detection: a word of caution [letter]