Detection of carriers and prenatal diagnosis of bleeding disorders.

Carrier detection and prenatal diagnosis in the three commonest bleeding disorders (hemophilia A and B and von Wilebrands disease) can be performed either phenotypically or genotypically. Phenotypic analysis for carrier detection results only in a probabilistic assessment whereas DNA analysis, either by direct defect detection or by DNA polymorphism based gene tracking, can result in an accuracy of effectively 100%. Direct defect detection is the method of choice but can be technically demanding. Polymorphism analysis is much simpler and is now being used in family studies world wide.