HTRA1 and age-related macular degeneration: Family-based linkage studies, genome-wide association studies (GWAS) studies and candidate gene approaches identified major common variants conferring AMD risk on chromosomes 1q31 and 10q26 within, respectively, complement factor H (CFH) (Y402H) and the age-related maculopathy susceptibility 2 (ARMS2) and adjacent high-temperature requirement factor (HTRA1/PRSS11) genes (8, S30–S33).