Isolation of a further anonymous informative DNA sequence from chromosome seven closely linked to cystic flbrosis

A library prepared from flow-sorted chromosomes was used to isolate single-copy sequences from chromosome seven. One euch sequence 7C22 haa been shown to be polymorphic for an EcoRI restriction site and to be informative for the study of CF in approximately 35% of matings. The segregation of the 7C22 alleles was followed through nineteen informative families with more than one child affected by cystic fibrosis. We report that the locus for 7C22 ie linked to the locus for cystic fibroeie at a recombination fraction of 0.045. This marker will prove useful in improving the accuracy and informativeness of prenatal diagnosis and in constructing a fine genetic map around the cystic fibrosio gene.