Sex determination of human embryos using the polymerase chain reaction and confirmation by fluorescence in situ hybridization.

Objective: To use fluorescence in situ hybridization to corroborate the polymerase chain reaction (PCR) preimplantation diagnosis of human embryos in three couples carrying a chromosome X-linked disease.

Setting: Clinical and research IVF laboratories.

Patients: Individuals undergoing preimplantation diagnosis.

Results: Four ETs were performed in couples undergoing preimplantation diagnosis by multiplex PCR or fluorescence in situ hybridization, resulting in the birth of two normal female twins. The result of another is pending. A total of 22 embryos were analyzed by PCR. Embryos that were diagnosed as being at risk of carrying the genetic abnormality (n = 8), embryos that failed diagnosis (n = 4), and genetically normal embryos that arrested development (n = 4) were further analyzed by fluorescence in situ hybridization. The sex of all 16 embryos was determined and confirmed the previous 12 preimplantation diagnoses by multiplex PCR. In addition, fluorescence in situ hybridization analysis allowed the detection of two aneuploid embryos, one XO and one XXY, previously diagnosed by PCR as a normal female and male. Two mosaics were also detected.

Conclusion: Polymerase chain reaction and fluorescence in situ hybridization are possible for preimplantation sex determination in cases of genetic sex-linked disease. Fluorescence in situ hybridization, however, supplies additional information about sex chromosome aneuploidy and is not susceptible to contamination or misdiagnosis of monosomy X.