HTRA1 and age-related macular degeneration: The 2 main loci identified involve: the activation of the complement system (3–9); and the age-related maculopathy susceptibility 2/high-temperature requirement A serine peptidase 1 (ARMS2-HTRA1) risk locus linked to overexpression of HTRA1 and accumulation of macrophages in the subretinal space with resultant inflammation (10).