[Analysis of X ba I polymorphism of FVIII gene and its application on prenatal diagnosis for hemophilia A].

Objective: To establish the linkage methods of X ba I polymorphisms specific for FVIII gene intron 22, and to find a rapid and simple system for haemophilia A (HA) carrier detection and prenatal diagnosis.

Methods: A long PCR to amplify FVIII gene intron 22 followed by X ba I digestion was used to assay the gene rate and heterozygosity rate of 206 unrelated people. Detection of intron 22 inversion by long distance PCR (LD-PCR) and XbaI, BclI, Hind III, DXS52, STR polymorphism within intron 13 and 22 by hereditary linkage analysis were assays in 20 HA pedigrees.

Results: The gene rate and polymorphism information contents of 206 people were 0.5475 and 0.4955 respectively, 7 of 20 HA families were diagnosed as intron 22 inversion, 6 of 13 non-inversion HA families were diagnosed by X ba I linkage analysis, 8 of 13 non-inversion HA families were diagnosed by two or more linkage analysis.

Conclusions: The improved X ba I linkage analysis is a specific and useful molecular diagnosis marker. LD-PCR and five-linkage analysis can be used in prenatal HA gene diagnosis.