Prenatal diagnosis of trisomy 12 mosaicism: normal development of a 3 years old female child: Trisomy 12 mosaicism is a rare chromosomal mosaicism in prenatal diagnosis by amniocentesis. In the literature we found at least 27 cases. 13 Pregnancies were terminated, with multiplecongenital anomalies (MCA) in 2 out of 13. Of the 12 liveborns with follow-up ranging from 0 to 5 years, 5 presented MCA and died within the first weeks. 2 Fetus died died during pregnancy and further data are lacking. A normal outcome, with limited follow up however, was reported in 7/12 liveborns without congenital anomalies and is well demonstrated in the presently reported girl. We describe the 3-years follow up in a girl with trisomy 12 mosaicism, detected by amniocentesis for advanced maternal age. She is a healthy girl with normal physical and psychomotor development.