1. Trisomy 21, also known as Down syndrome, is a genetic disorder caused by the presence of an extra chromosome 21.
染色体21三倍体，也称为唐氏综合症，是由额外的21号染色体引起的遗传紊乱。

2. trisomy 18, also known as Edwards syndrome, is a rarer chromosomal disorder that affects multiple systems in the body.
染色体18三倍体，也被称为爱德华氏综合征，是一种较为罕见的影响身体多个系统的染色体异常情况。