BARD1 and breast cancer: The subgroup of index patients with BC and heterozygous germline LoF variants in BARD1 showed a younger mean AAD of BC (42.3 years; range 24–60 years) compared with the overall sample of index patients with BC (48.6 years; range 17–92 years), with differences reaching levels of significance (P = 0.00347; Student’s t test).