Association between PAX9 single-nucleotide polymorphisms and nonsyndromic cleft lip with or without cleft palate

The purpose of this study was to investigate the contribution of PAX9 gene to the risk of nonsyndromic cleft lip with or without cleft palate (NS-CL/P). The samples consisted of 142 Korean NS-CL/P families (90 males and 52 females; 9 cleft lip, 26 cleft lip and alveolus, and 107 cleft lip and palate; 76 trios and 66 dyads). A total of 10 single-nucleotide polymorphisms (SNPs) were tested for association with Korean CL/P case-parent trios using transmission disequilibrium test (TDT) and conditional logistic regression models. The minor allele frequency, heterozygosity, and a χ test for Hardy-Weinberg equilibrium at each SNP were computed between parents. Pairwise linkage disequilibrium was computed as both D' and r2 for all SNPs. Both allelic and genotypic TDTs were performed for individual SNPs using family-based association test program. Sliding windows of haplotypes consisting of 2 to 8 SNPs were tested using haplotype-based association test program. Genotypic odd ratios were obtained from conditional logistic regression models using STATA software. The family-based TDT using individual SNPs and 2- to 8-SNP haplotypes of the gene indicated a significant association at rs17104928 (P = 0.014). The haplotype analysis revealed that the association was most significant for the haplotype consisting of 3 SNPs (rs2073247, rs17104928, and rs17176643; P = 0.007). G/A heterozygote at rs17104928 had a significantly increased association with NS-CL/P (genotypic odd ratio, 2.88; 95% confidence interval, 1.42-5.84; P = 0.0014, dominant model). The high-risk SNP and genotype may provide a better understanding of the etiologic role of PAX9 gene in NS-CL/P and potential options for genetic counseling.