[In-situ hybridization on chorionic villi chromosomes].

Novel techniques for the prenatal diagnosis of inherited defects are currently being developed. The long-range aim is to be able to predict precisely, at an early stage of fetal development, the tendency of the fetus to develop multiple genetic, congenital or acquired diseases. We adapted the technique of gene mapping by in-situ hybridization for use with chromosomes from fetal chorionic villi sampling (CVS). Refined mapping of the genes coding for cholinesterase (CHE) in comparison with the haptoglobin and the transferrin receptor genes on CVS chromosomes Nos. 3 and 16 revealed 3 CHE genes in positions 3q21, 3q26, and 16q12. In view of genetic linkage data, at least 2 of these appear to be potentially active. These findings demonstrate that genes, for which molecularly cloned DNA probes are available, may be localized on CVS chromosomes by comparing their localization with that of known genes after in-situ hybridization. The implications for prenatal diagnosis are promising.