Genetic Markers in Breast Cancer- How Far Have We Come from BRCA1?

Breast cancer is the most common malignancy that develops in women worldwide, its incidence  continues  to  rise  and  it  is  responsible  for  the  highest  death  rates.  Breast cancer  can  be  classified  as  sporadic  or  familial  -  the  strongest  risk  factor  today  is  a family  history.  Germline  mutations  in  high-penetrance  breast  cancer  susceptibility genes BRCA1 and BRCA2 have been strongly implicated in the genetic predisposition of approximately 20% of familial breast cancers. Although BRCA1 and BRCA2 do not account  for  all  familial  breast  cancers,  there  are  currently  no  other  genes  that  have been identified which segregate with familial breast cancer as strongly. Despite large-scale  attempts  to  identify  genetic  risk  factors  associated  with  breast  cancer,  the  variants identified through genome-wide association studies (GWAS), only confer a modest increase in risk of breast cancer and at present lack clinical utility. This review will discuss  the  known  genetic  risk  factors  for  developing  breast  cancer  and  how  far  the field has progressed since the identification of BRCA1.