[Molecular genetics and prenatal diagnosis].

Recombinant DNA techniques have provided new insight into genetic and prenatal diagnosis during the last 10 years. Human gene mapping data are increasing exponentially due to molecular biology advances. Most analyses are possible from chorionic villi biopsy specimens as early as the 10th week of fetal life. When the gene is known and cloned, the diagnosis is regularly made by using the polymerase chain reaction technique; when the gene is unknown but mapped, the restriction fragment length polymorphism technique is used. However, these methods for prenatal assessment require a reliable diagnosis of index case disease and a preliminary familial DNA study.