Materials and Methods Patients and Family Members

gene and the heterogeneous nature of mutations, direct gene analysis often becomes difficult.5,6 Carrier screening and prenatal diagnosis of hemophilia A usually depend on haplotype analysis using restric-tion fragment length polymorphisms (RFLPs) and short tandem repeat (STR) markers to trace the defective FVIII gene within the family. Because the heterozygosity rates for different RFLPs differ eth-nic groups,7 it is important to have data on the infor-mativity of various markers in different populations. We have examined the utility in carrier detection of 3 polymorphic sites at intron 18 (BclI), intron 19 (HindIII), and intron 22 (XbaI) in 100 patients with hemophilia A and their relatives at risk in north India