A novel mutation of Arg306 of factor V gene in Hong Kong Chinese.

We have analyzed 83 unrelated Hong Kong Chinese for the presence of genetic variants of factor V gene. Forty-three of them had a history of deep vein thrombosis. The DNA sequence variations of exons 7, 10, and 13, where the codons for Arg306, Arg506, and Arg679 are located, respectively, were studied by denaturing gradient gel electrophoresis. The G1691-->A (Arg 506-->Gln) mutation in exon 10 was not detectable in any of the 83 subjects. However, a high allelic frequency for the G1628-->A (Arg 485-->Lys) substitution was detectable in the same exon. We have also identified a novel DNA sequence mutation (A1090-->G) in exon 7 that resulted in Arg 306-->Gly substitution in 2 thrombotic patients and 1 nonthrombotic subject. Fresh blood samples were available from one of them for analysis of activated protein C resistance and the result was negative. Variation of DNA sequence was not found in exon 13 in any of our 83 subjects. The results of this study showed that, although the Arg 506-->Gln mutation was rarely found in the Hong Kong Chinese population, a different mutation site such as A 1090-->G in exon 7 of the factor V gene (Arg 306) may be of clinical importance.