Carrier detection by DNA linkage analysis in eighty Thai hemophilia A families.

DNA linkage analysis was performed in Thai hemophilia A families to evaluate its value for carrier detection. Both intragenic and extragenic polymorphic DNA regions of the factor VIII gene, including Bcl I-RFLP in intron 18, microsatellites (CA repeats) in introns 13 and 22, and extragenic Stl4 (DXS 52) VNTR, were amplified by polymerase chain reaction (PCR) before analyses by appropriate electrophoretic procedures. A total of 80 Thai hemophilia A families (48 with a family history and 32 with a sporadic case), containing 349 DNA samples from 90 hemophilia A patients, 143 parents, and 116 relatives, were analyzed. Heterozygosities in the patients' mothers from both families with a family history and with a sporadic case were observed in 71 out of 80 families (88.75%) for all polymorphic DNA markers analyzed. The carrier status could be identified in 36 females and excluded in 44 females. This result indicates that the DNA linkage analysis can be used for carrier detection or exclusion in the majority of Thai hemophilia A families. It should also be useful for prenatal diagnosis in families at risk of hemophilia A, which is part of the prevention and control of this disease.