An integrative, genomic, transcriptomic and network-assisted study to identify genes associated with human cleft lip with or without cleft palate.

BACKGROUND: Cleft lip with or without cleft palate (CL/P) is one of the most common congenital human birth defects. A combination of genetic and epidemiology studies has contributed to a better knowledge of CL/P-associated candidate genes and environmental risk factors. However, the etiology of CL/P remains not fully understood. In this study, to identify new CL/P-associated genes, we conducted an integrative analysis using our in-house network tools, dmGWAS [dense module search for Genome-Wide Association Studies (GWAS)] and EW_dmGWAS (Edge-Weighted dmGWAS), in a combination with GWAS data, the human protein-protein interaction (PPI) network, and differential gene expression profiles. RESULTS: A total of 87 genes were consistently detected in both European and Asian ancestries in dmGWAS. There were 31.0% (27/87) showed nominal significance with CL/P (gene-based p < 0.05), with three genes showing strong association signals, including KIAA1598, GPR183, and ZMYND11 (p < 1 x 10(- 3)). In EW_dmGWAS, we identified 253 and 245 module genes associated with CL/P for European ancestry and the Asian ancestry, respectively. Functional enrichment analysis demonstrated that these genes were involved in cell adhesion, protein localization to the plasma membrane, the regulation of the apoptotic signaling pathway, and other pathological conditions. A small proportion of genes (5.1% for European ancestry; 2.4% for Asian ancestry) had prior evidence in CL/P as annotated in CleftGeneDB database. Our analysis highlighted nine novel CL/P candidate genes (BRD1, CREBBP, CSK, DNM1L, LOR, PTPN18, SND1, TGS1, and VIM) and 17 previously reported genes in the top modules. CONCLUSIONS: The genes identified through superimposing GWAS signals and differential gene expression profiles onto human PPI network, as well as their functional features, helped our understanding of the etiology of CL/P. Our multi-omics integrative analyses revealed nine novel candidate genes involved in CL/P.