||Perhaps slightly lower risk for breast cancer in BRCA1/2 mutation carriers?
rs165631, also known as p.L203, represents a synonymous variant in the COMT gene; the minor rs165631(T) allele has a population allele frequency of 1% (based on exome sequencing of 60,000 individuals).
Admittedly based on only a handful of cases, a preliminary report hunting for variants that might delay or prevent breast cancer in women carrying either disease-causing BRCA1 or BRCA2 mutations observed that the rs165631(T) allele was present in 5 of 15 women with BRCA1/2 mutations (but not breast cancer), while it was not present in any of 25 women with breast cancer (in a different group of women). The authors believe their study "suggests an intriguing genetic correlation", i.e. that rs165631(T) carriers who harbor BRCA1 or BRCA2 mutations might be at lower risk for breast cancer than non-carriers (of this COMT allele).[PMID 28538113]