Moreover, germline exploration has led to documentation of rare, high-penetrance (BRCA1, BRCA2, TP53), moderate penetrance (PTEN, STK11, CDH1, ATM, CHEK2, BRIP1, PALB2) and common, low penetrance risk alleles for developing breast cancer (Li Volti et al., 2011; Salomone et al., 2013; Tibullo et al., 2013; Pomara et al., 2016; Barone et al., 2017; Hahnen et al., 2017; Nik-Zainal and Morganella, 2017; Rizvi et al., 2017). The gene discussed is PTEN; the disease is breast cancer.