Association Studies Between Regulatory Regions of IRF6/TP63 Genes and Nonsyndromic Oral Clefts

Objective: To evaluate genetic variants within the regulatory regions of interferon regulatory factor 6 (IRF6) and TP63 for the etiology of nonsyndromic oral clefts risk factors. Design: We performed allelic transmission disequilibrium test analysis on 5 eligible single-nucleotide polymorphisms (SNPs) and SNP haplotypes using the Family-Based Association Test. Participants: The study sample consisted of 334 case-parent trios of nonsyndromic oral clefts from Taiwanese population, separated into nonsyndromic cleft lip/palate (NSCUP) and nonsyndromic cleft palate only (NSCPO) groups. Results: We found all 3 selected SNPs of the IRF6 gene show significant association with nonsyndromic oral clefts (rs2235371, P = 5.10E-07; rs642961, P = .00194; and rs77542756, P = 9.08E-07). Haplotype analyses identified 3 possible SNP combination haplotypes in the IRF6 gene and found that C-G-G showed significant undertransmission (P = .058), whereas 2 other haplotypes, T-G-A and C-A-G (P = 2.71 E-06 and P = 5.00E-04, respectively), were significantly overtransmitted to the NSCL/P children but not to the NSCPO children. For the TP63 gene, we failed to detect evidence of nonsyndromic oral cleft association in the 2 SNPs within the TP63 large intron I region. Conclusions: We used a family-based analysis in 334 Taiwanese case-parent trios to evaluate selected SNPs of IRF6 genes and TP63 genes for a risk of orofacial clefting. This study provides additional evidence for an association between IRF6 and NSCL/P, including the genetic variants within the 5'-noncoding region of the gene. We also confirmed that NSCL/P and NSCPO individuals belong to different groups. For the TP63, our data did not favor the direct involvement of TAp63 isoforms during orofacial development.