Sequencing the exons and proximal 5′ region of OPRK1 in 16 human samples (half carrying the lower risk and half carrying the higher risk haplotype) led to the detection of six new SNPs (reported to dbSNP: rs35970029, rs34418807, rs35991105, rs34709943, rs35373196, rs35160174). At all of the SNPs, the lower risk samples were homozygous for the reference sequence, whereas some of the higher risk samples were heterozygous. We also detected a new complex indel involving the deletion of 11 bp from −1975 to −1985 (all positions are relative to the reference genome sequence NT_008183.18 and the translation start site of OPRK1, RefSeq NM_000912) and the insertion of 841 bp at −1986 bp relative to the reference genome sequence, for a net insertion of 830 bp (reported to dbSNP: rs35566036). All eight of the samples with the lower risk haplotype lacked the indel and matched the reference genome sequence. All the eight of the samples with the higher risk haplotype had a copy of the indel. A diagram of the gene, based upon the reference sequence, is shown in Figure 1. The
