IRX1 and Kyphoscoliosis: The strongest association was with rs12517904 (P = 0.00004), located 6.5 kb downstream from IRX1. In one family, the genotypes of nine variants differed from the reference allele in all individuals with kyphoscoliosis, and two of three individuals with scoliosis, but did not differ from the reference allele in all other genotyped individuals.