BRCA1 and Hereditary breast and ovarian cancer syndrome: The increase in genetic sequencing capability combined with the decrease in the cost of testing has altered both regulatory policy and clinical oncology practice Well-known examples of clinically important cancer susceptibility syndromes such as those caused by genetic mutations in highly penetrant genes such as <i>BRCA1/2</i> hereditary breast-ovarian cancer syndrome genes have provided the framework for the practice of clinical cancer genetics.