Association Between DLX4 Polymorphisms and Nonsyndromic Orofacial Clefts in a Chinese Han Population

Distal-less 4 ( DLX4) was recently identified as the causative gene for a syndromic form of cleft lip with or without cleft palate, and further biological analyses have established the importance of Dlx4 gene in craniofacial development, which suggested DLX4 as a promising candidate to further investigate any possible association between DLX4 polymorphisms and risk to nonsyndromic orofacial clefts (NSOFCs).

Single-nucleotide polymorphisms (SNPs) with minor allele frequency >5% in the Han Chinese population which locate in the 5' flanking region, 5'/3'-untranslated region, or coding region with nonsynonymous changes in DLX4 were selected. Four SNPs (rs58769681, rs1058562, rs1058564, and rs8066341) were thus included in the following genotyping using the TaqMan 5'-exonuclease allelic discrimination assay in a case-control cohort with 1522 individuals.

None of SNPs were associated with NSOFCat the allele and genotype levels in general and stratified single-marker analysis, including genotypic distributions under different modes of inheritance. In linkage disequilibrium (LD) analysis, we found strong LD ( r² > 0.8) between any 2 of the SNPs, respectively. Further haplotyping identified haplotypes C-C (formed by rs1058564 and rs1058562) and C-C-A (formed by rs1058564, rs1058562, and rs58769681) which reached the significance threshold ( P < .05); nevertheless, none of them survived the multiple comparison correction.

Our findings indicated the hypothesis that DLX4 variants contributing to NSOFC risk should be interpreted with caution. Further replications in diverse ethnic origins and larger cohorts are still warranted.