NPY is located on 7p15.1 and is 7.7 kb in size; NPY2R is on 4q32.1 and is 8.6 kb in size. The other two receptor genes, NPY1R and NPY5R, are only 8kb apart, span 28 kb on 4q32.2 and were analyzed together. SNPs distributed throughout the 4 genes were selected from public databases, primarily dbSNP (http://www.ncbi.nlm.nih.gov/SNP/), based on their spacing and available allele frequencies. At the time some SNPs were selected, allele frequencies were not available. To determine allele frequencies and to test the quality of the assays, SNPs were genotyped in two sets of samples, each consisting of 40 unrelated individuals from the Coriell European- and African-American diversity samples; only SNPs in Hardy Weinberg equilibrium in both test groups were genotyped on the COGA sample.
