Summary
The molecular basis of haemophilia B is heterogeneous and many mutations of the Factor
IX (FIX) gene have been characterised. Using the allele-specific arrayed primer extension
(ASAPEX) technology, we have designed a FIX array to simultaneously analyse 69 mutations
found in British, Thai and Chinese patients. This technology overcomes the problem
of multiple reverse dot-blot analysis and has a 100% accuracy in the detection of
both affected subjects and carriers in families with known mutations. In seven unknown
mutations from Thailand, the array could detect the specific mutation in five and
in the remainders the normal primer at specific spots failed to extend due to a mutation
a few nucleotides upstream, thus allowing their identification. Hence this FIX array
can detect 53% of the 2891 mutation entries in the FIX database. Each of the microarray
slide can be used for three different test samples and would be useful for carrier
testing for common mutations and prenatal diagnosis. It is simpler and more cost effective
than genome sequencing and would be particularly useful in laboratories with limited
technical capabilities.
Keywords
Haemophilia B - FIX microarray - AS-APEX - FIX mutations
