BRCA1 and BRCA2 gene

Both BRCA1 and BRCA2 genes are large, containing 24 and
26 exons respectively. Since being isolated, a considerable
number of mutations have been described in both genes – over
250 in BRCA1 and over 100 in BRCA2. Up to 90% of these
mutations are predicted to produce a truncated protein. This
makes it possible to screen for mutations in the large central
exon 11 using the protein truncation test. The remaining exons
are generally screened one-by-one using methods such as
SSCP/heteroduplex analysis or DNA sequencing.
Population-specific founder mutations have been found in
eastern European, Ashkenazi Jewish and Icelandic
populations. Screening for the common mutation is therefore
undertaken as the first step in investigating families from
these population groups.