Carriers of the common Icelandic BRCA2 999del5 mutation were found to have their risk of breast cancer further increased if they also carried the BARD1 variant: the frequency of the BARD1 variant allele was 0.047 (OR = 3.11, 95% CI 1.16–8.40,p = 0.046) in 999del5 carriers with breast cancer. The gene discussed is BRCA2; the disease is breast carcinoma.