thanks a lot!

来源: 于 2009-03-18 05:10:25 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

Down syndrome (trisomy 21) is the most commonly recognized....

That means down is trisomy. my probability is only 1/3500. great. no need for invasive test. haha.