Most common Familial Breast cancer gene:

Ans. (a) BRCA 1(Ref Sabiston 20th Edition 832)* Hereditary breast cancer - 5-10%# BRCA1 - 45% (MC hereditary Breast cancer)# BRCA2 - 35%# P53(Lifraumeni) - < 1%# Peutz jeughers, Cowden disease, Muir torre syndrome, Ataxia telangiectasia all less than 1% each.