|| greatly increased risk of breast cancer
|| BRCA2 variant considered pathogenic for breast cancer
This variant represents the BRCA2 gene 6174delT mutation. As reported by 23andMe, the normal genotype is (I;I), which is also abbreviated II. The genotypes containing the causal/pathogenic variants are (D;I) and the even rarer (D;D).
For information about causal/pathogenic BRCA2 mutations and what they imply about the odds of developing breast cancer, please see the BRCA2 page and links from that page.
i4000379 is the identifier used by 23andMe for the 6174delT mutation that is rs80359550 as identified in public SNP databases.
Additional BRCA information may be found in numerous places online, and within 23andMe, here.
In addition to i4000379, the other names used by 23andMe for the most common causal mutations are i4000377 and i4000378.