Pregnancies from biopsied human preimplantation embryos sexed by Y-specific DNA amplification

Abstract

Over 200 recessive X chromosome-linked diseases, typically affecting only hemizygous males, have been identified. In many of these, prenatal diagnosis is possible by chorion villus sampling (CVS) or amniocentesis, followed by cytogenetic, biochemical or molecular analysis of the cells recovered from the conceptus. In others, the only alternative is to determine the sex of the fetus. If the fetus is affected by the defect or is male, abortion can be offered. Diagnosis of genetic defects in preimplantation embryos would allow those unaffected to be identified and transferred to the uterus. Here we report the first established pregnancies using this procedure, in two couples known to be at risk of transmitting adrenoleukodystrophy and X-linked mental retardation. Two female embryos were transferred after in vitro fertilization (IVF), biopsy of a single cell at the six- to eight-cell stage, and sexing by DNA amplification of a Y chromosome-specific repeat sequence. Both women are confirmed as carrying normal female twins.

KIE: British researchers report on the first established pregnancies after preimplantation embryos were sexed after in vitro fertilization and those identified as female were placed in the uterus. The procedure involved the embryos of five couples at risk for transmitting recessive x-linked diseases to male offspring. Handyside, et al. describe the method by which the embryos were sexed using DNA amplification. They report one unconfirmed clinical pregnancy and two confirmed pregnancies with normal female twins.