2-way SNP and a representative gene network. (a) There are 35 edges and 45 nodes in Figure 4a, where each node denotes a SNP locus. An edge represents a 2-way SNP combination that has a strong association with the phenotype. The yellow SNPs (nodes) have been reported to be associated with age-related macular degeneration (AMD). (b) In Figure 4b, the nodes and edges are mapped from nodes and edges from Figure 4a, in which a node denotes a gene, and each edge represents a 2-way SNP combination that is mapped to two genes. NA denotes non-gene coding regions; there are multiple NA–NA edges because multiple SNP–SNP pairs were mapped to non-gene-coding regions. The greater the number of edges between two gene nodes, the more the SNP combination maps into the two genes. The yellow genes (nodes) are believed to be associated with AMD. In node NA, there are many edges, which means there are multiple SNP combinations in the non-coding region.