Gene Mutations in Hereditary Breast Cancer- A Review

The most prevalent form of cancer in females is breast cancer. Roughly 5%-10% of breast cancers are hereditary, and they are associated with Germline gene mutations, inherited from parents. Germline gene mutations increase the risk of developing cancer earlier in life compared to noninherited cases (sporadic cancer). BRCA1 and BRCA2 are well-studied tumour suppressor genes associated with hereditary breast cancer. Even though mutations in BRCA1 and BRCA2 are assumed to responsible the majority of hereditary breast cancers cases, many other breast cancer susceptibility genes have been identified in the last few decades. Identification of many germline mutations was possible due to advance sequencing technologies. Most of these genes are belongs to tumour suppressors and DNA damage repair gene families (DNA double-strand break repair and DNA mismatch repair). These genes play a vital role in genomic stability and cell cycle control suggesting that any alteration in these genes trigger uncontrolled growth and tumour formation. These genes are categorized according to the penetrance level, the proportion of carriers express the associated trait of the mutated gene. Mutations in high penetrance genes such as BRCA1, BRCA2, TP53, PTEN, and SKT11 greatly increase the risk of developing breast cancer. Moderate penetrance gene such as PALB2, ATM, CHEK2, BARD1, BRIP1 and low penetrance gene such as PARP4, CASP8, TOX3 confer moderate to low increase risk of developing breast cancer. Aim of this review is to summarize genes associated with hereditary breast cancer according to their penetrance level (high, moderate and low penetrance).