[Prenatal diagnosis in a family carrying the fragile X syndrome using recombinant DNA technics].

The prenatal diagnosis in a family carrying the Fragile Chromosome X Syndrome (sex linked mental retardation) has been performed using Recombinant DNA techniques. The use of these techniques together with cytogenetics and prenatal diagnosis using chorial biopsy, have enabled the diagnosis of the disease on a male foetus on the twelfth week of pregnancy. Similarly, we have been able to confirm the carrier state of the mother (proven) and the grand mother, and furthermore, the non affected condition of an older son to this mother. The results obtained reveal the importance of the new molecular techniques applied to the diagnosis of certain diseases with a genetic origin.