Prenatal DNA diagnosis of Noonan syndrome in a fetus with massive hygroma colli, pleural effusion and ascites.

Prenatal molecular genetic diagnosis for Noonan syndrome I is reported. Noonan syndrome was suspected because of large cystic hygroma colli, massive pleural effusion and ascites at 23 weeks of gestation and normal karyotype (46,XX). DNA was prepared from amnion cells and screened for mutations in the PTPN11 gene.