NTN1 and age-related macular degeneration: We tested the existence of epistatic relationships within the NTN1-DCC-cAMP-CN-NFAT sub-pathway using data from the NEI Study of Age-Related Macular Degeneration (NEI-AMD, dbGaP Project 000182) to find strong NTN1-RYR2 (rs9674710-rs12046077, P< 9.88 x 10–5; rs4791779-rs4659491, P< 1.37 x 10–5) and DCC-CACNA1C (rs3915401-rs1009281, P< 2.28 x 10–5) associations.