Least risk of CA breast is seen in -

Ans. is 'd' i.e. Ataxia telangiectasia Only about 5 to 10% of breast cancers are caused by inheritance of germline mutations most important of which are BRCA-1 & BRCA-2.Percent Incidence of Sporadic, Familial, and Hereditary Breast CancerSporadic breast cancer 65-75%Familial breast cancer 20-30%Hereditary breast cancer 5-10%BRCA-145% BRCA-235% p53 (Li-Fraumeni Syndrome)1% STK 11/LKB1 (Peutz-Jeghners syndrome)<1% PTEN (Cowden disease)<1% MSH2/MLH1 (Muir Torre syndrome)<1% ATM (Ataxia-telangiectasia)<1% Unknown20%