An RFLP for glycoprotein A (MN) is in linkage disequilibrium with MN and Ss.

Using a cDNA for glycophorin A (MN), we screened 10 unrelated Caucasians using 22 restriction enzymes for RFLPs. A common StuI RFLP was identified and shown to be in marked linkage disequilibrium with both the MN and Ss blood-group antigens in a larger group of unrelated Caucasians. This provides a DNA marker for a locus that has been of major importance in genetic and population studies. The demonstrated disequilibrium will prove useful in localizing the gene for glycophorin B and in studies of genetic and physical distances on human chromosomes.