BRCA1 and breast cancer: For example, de la Hoya and colleagues demonstrated that improvements to understanding of native alternative splicing events in the breast cancer susceptibility gene BRCA1 show that the risk of developing cancer is unlikely to be increased for carriers of truncating variants in exons 9 and 10, or indeed other alleles that retain 20–30% tumour-suppressor function, even where such variants had been previously characterized as pathogenic [166].