Preimplantation genetic diagnosis for Down syndrome pregnancy.

[monosomy 21]

To evaluate the effect of preimplantation genetic diagnosis (PGD ) conducted for women who had Down syndrome pregnancy previously .Trisomy 21 was diagnosed by using fluorescence in site hybridization (FISH ) before embryo transfer in two women who had Down syndrome pregnancies . Each received one or two PGD cycles respectively .Case 1 : one PGD cycle was conducted , two oocytes were fertilized and biopsied . One embryo is of trisomy 21 and the other of monosomy 21 . No embryo was transferred . Case 2 : two PGD cycles were conducted , in total , sixteen oocytes were fertilized and biopsied . Four embryos were tested to be normal , six of trisomy 21 , and one of monosomy 21 . Five had no signal . Four normal embryos were transferred but no pregnancy resulted .For couples who had pregnancies with Down syndrome previously , PGD can be considered , and has been shown to be an effective strategy .