BACKGROUNDThe receptor tyrosine kinase-like orphan receptor 2 (ROR2) gene has been recently shown to play important roles in palatal development in animal models and resides in the chromosomal region linked to non syndromic cleft lip with or without cleft palate in humans. The aim of this study was to investigate the possible association between ROR2 gene and non-syndromic oral clefts.

METHODSHere we tested 38 eligible single-nucleotide polymorphisms (SNPs) in ROR2 gene in 297 non-syndromic cleft lip with or without cleft palate and in 82 non-syndromic cleft palate case parent trios recruited from Asia and Maryland. Family Based Association Test was used to test for deviation from Mendelian inheritance. Plink software was used to test potential parent of origin effect. Possible maternally mediated in utero effects were assessed using the TRIad Multi-Marker approach under an assumption of mating symmetry in the population.

RESULTSSignificant evidence of linkage and association was shown for 3 SNPs (rs7858435, rs10820914 and rs3905385) among 57 Asian non-syndromic cleft palate trios in Family Based Association Tests. P values for these 3 SNPs equaled to 0.000068, 0.000115 and 0.000464 respectively which were all less than the significance level (0.05/38 = 0.0013) adjusted by strict Bonferroni correction. Relevant odds ratios for the risk allele were 3.42 (1.80 - 6.50), 3.45 (1.75 - 6.67) and 2.94 (1.56 - 5.56), respectively. Statistical evidence of linkage and association was not shown for study groups other than non-syndromic cleft palate. Neither evidence for parent-of-origin nor maternal genotypic effect was shown for any of the ROR2 markers in our analysis for all study groups.

CONCLUSIONOur results provided evidence of linkage and association between the ROR2 gene and a gene controlling risk to non-syndromic cleft palate.