THE MOLECULAR-BASIS OF THE KIDD BLOOD-GROUP POLYMORPHISM AND ITS LACKOF ASSOCIATION WITH TYPE-1 DIABETES SUSCEPTIBILITY

The Kidd blood group locus encodes a urea transporter which is express ed on human red cells and in the kidney, This gene is located on chrom osome 18q12, and evidence for linkage and association with type 1 diab etes mellitus has been reported, To investigate this further, the gene tic basis for the blood group Jk(a)/Jk(b) polymorphism was first deter mined by sequencing reverse-transcribed reticulocyte RNAs from Jk(a+b- ) and Jk(a-b+) donors, The Jk(a)/Jk(b) polymorphism was caused by a tr ansition (G838A), resulting in a Asp280Asn amino acid substitution and an MnA restriction fragment length polymorphism (RFLP), Using the MnA RFLP, we found that the Jk(a)/Jk(b) polymorphism was not in linkage d isequilibrium with type 1 diabetes in 228 multiplex UK and US families tested.