First trimester diagnosis of cystic fibrosis with linked DNA probes.

In late 1985 the cystic fibrosis (CF) gene was located to chromosome 7, at 7q 22/31. Several restriction fragment length polymorphism (RFLP) markers are closely linked to the CF gene. These markers permit accurate first-trimester prenatal diagnosis based on analysis of chorionic villus DNA by studies of families with one or more affected children. In our laboratory 13 families at risk of having a child with CF have been counselled by the use of linked DNA probes: xV-2c; pCS.7; Met H; Met D; pJ3.11; KM 19. In all cases one or more of the mentioned probes were sufficiently informative to allow first-trimester prenatal diagnosis. In four of the 13 families tested prenatal diagnosis have been performed.