We constructed a high-density map of single-nucleotide polymorphisms (SNPs) present within a 31-kb region of human chromosome 13q31 that contains the human counterpart of the rabbit ITR gene, which encodes a rhodopsin-like G protein-coupled receptor associated with vascular remodeling. The elements of human ITR cDNA were distributed in 27,452 bp of genomic DNA; the nine exons ranged in size from 50 bp to 2271 bp, with an average size of 392 bp. We isolated a total of 22 SNPs from the ITR locus by systematically screening genomic DNA from 48 healthy Japanese individuals; three SNPs were present in the 5' flanking region, two in coding elements, 12 in introns, and five in the 3' untranslated region. By comparing our data with SNPs deposited in the dbSNP database in the National Center for Biotechnology Information, 19 of the 22 SNPs (86%) were considered to be novel. The map presented here should help in evaluating the role of human ITR in cardiovascular diseases, in other diseases mapped to this segment on chromosome 13q31, and in a variety of pharmacogenetic effects.