Possible misdiagnosis using the Xba I polymorphism for prenatal diagnosis of haemophilia A

Abstract
A mother of two haemophilia A sons presented at 7 weeks pregnancy for a prenatal diagnosis. Southern blot analysis of haemophilia DNA at the factor VIII intron 22 Xba I restriction fragment length polymorphism (RFLP) site revealed an Xba I haplotype of A-B+C-. This haplotype has been alluded to but not reported before, and when a 1.6 kb Bst XI fragment of p482.6 is used as a probe the resulting band pattern is similar to that of females heterozygous at site A.