IRF6 polymorphisms in Brazilian patients with non-syndromic cleft lip with or without palate

Non-syndromic orofacial clefts have a complex etiology due to the contribution from both genetic and environmental risk factors, as well as the interaction between them. Among the more than 15 susceptibility loci for non-syndromic orofacial clefts with considerable statistical and biological support, the IRF6 is the most validated gene by the majority of studies. Nonetheless, in genetically heterogeneous populations such as Brazilian, the confirmation of association between non-syndromic orofacial clefts and IRF6 common variants is not a consolidated fact and unrecognized IRF6 variants are poorly investigated.

The aim of this study was to investigate the association of IRF6 polymorphisms with non-syndromic orofacial clefts development in a population from northeast Brazil.

Blood samples of 186 non-syndromic orofacial clefts patients and 182 controls from Rio Grande do Norte, Brazil, were obtained to analyze IRF6 polymorphisms (rs2235371, rs642961, rs2236907, rs861019, and rs1044516) by real-time polymerase chain reaction. Non-syndromic orofacial clefts patients were classified in cleft lip and palate, cleft palate only and cleft lip only groups.

The genotype and allele frequencies of single nucleotide polymorphism rs2235371 in IRF6 showed significant differences in patients with cleft palate when compared to the controls, whereas no association was shown between rs642961, rs2236907, rs861019, and rs1044516 and non-syndromic orofacial clefts.

The association found between rs2235371 and isolated cleft palate should be interpreted with caution due to the low number of individuals investigated, and more studies with larger sample size are needed to confirm these association. In addition, there is a lack of association of the rs642961, rs2236907 and rs861019 polymorphisms with non-syndromic orofacial clefts susceptibility.