Mutations in BRCA-1 or BRCA-2 are both autosomal dominant mutations, which can be inherited and cause familial breast cancer.

BRCA-1和BRCA-2的突变都是常染色体显性突变，可被遗传并导致家族性乳腺癌。

There are two general types of gene mutations. One type, dominant mutation, is caused by an abnormality in one gene in a pair.

基因突变有两种一般类型。一种类型的显性突变是由一对中一个基因的异常引起的。

There are also genetic risk factors like having the BRCA-1 or BRCA-2 mutation, which are both autosomal dominant mutations, which in addition to ovarian cancer, carry with them an increased risk of breast cancer.

还有遗传相关的风险因素，如BRCA-1和BRCA-2突变，它们都是常染色体显性突变；除了卵巢癌之外，携带它们也会增加乳腺癌患病风险。

In general, deadly viruses do not last long because they kill their  host before infecting many other people; the mild ones can spread much more effectively,   so they tend to become the dominant mutation.

一般来说，致命病毒不会持续很长时间，因为它们会在感染许多其他人之前杀死宿主；温和的可以更有效地传播，因此它们往往会成为显性突变。