Identification of common non-coding variants at 1p22 that are functional for non-syndromic orofacial clefting

Genome-wide association studies (GWAS) do not distinguish between single nucleotide polymorphisms (SNPs) that are causal and those that are merely in linkage-disequilibrium with causal mutations. Here we describe a versatile, functional pipeline and apply it to SNPs at 1p22, a locus identified in several GWAS for non-syndromic cleft lip with or without cleft palate (NS CL/P). First we amplified DNA elements containing the ten most-highly risk-associated SNPs and tested their enhancer activity in vitro , identifying three SNPs with allele-dependent effects on such activity. We then used in vivo reporter assays to test the tissue-specificity of these enhancers, chromatin configuration capture to test enhancer–promoter interactions, and genome editing in vitro to show allele-specific effects on ARHGAP29 expression and cell migration. Our results further indicate that two SNPs affect binding of CL/P-associated transcription factors, and one affects chromatin configuration. These results translate risk into potential mechanisms of pathogenesis. Many genetic variants have been associated with complex congenital disorders, but their function is not always clear. Here, the authors develop a pipeline to functionally characterize such variants, and show potential roles for three SNPs in non-syndromic cleft lip and palate.