**7.3 Candidate genes**

Strategies of genomic search for disease genes are essentially free of a hypothesis to find genes or loci with susceptibility to a disease entity or quantitative trait. For keratoconus, mutation analysis in many candidate genes have also been attempted to find disease causative genes, some followed a biological hypothesis and some based on high GWAS significance. More than 50 SNPs in about 20 genes showing association with keratoconus have been studied in various ethnic populations [70, 95]. They include *FOXO1* [96]; ZNF469 [97]; *COL4A4* [98]; *COL4A3* [99]; *VSX*1 [100, 101]; *COL5A1* [102]; *MPDZ-NFIB* [102, 103]; *IL1B* [104, 105]; *HGF* [84]; *LOX* [85, 106]; and *IL1RN* [107]. Some of these genes have been studied in many populations with inconsistent results.
