[Sex determination of the embryo by DNA studies of chorionic villi samples]

The first step in the prenatal diagnosis of X-linked genetic disorders is the determination of the sex of the fetus. A new method for this purpose is based on recombinant DNA technology. The authors give a short account on their experiences with a Y specific DNA probe. Fetal DNA was prepared from chorionic villi taken at the 8th-12th weeks of gestation. The DNA was hybridised with the Y specific probe. This probe was isolated from the 3,4 kilobase human repeat sequence derived from heterochromatin of the Y chromosome and had 1000 times more affinity for male DNA than for female DNA. The method based on hybridisation with the Y specific probe should facilitate first-trimester prenatal sex determination of X-linked genetic disorders.