Genome-wide association studies have identified 52 genetic variants in 34 loci independently associated with AMD.7,8,9 The 2 loci most commonly associated with AMD are the complement factor H (CFH)–complement factor H–related 5 (CFHR5) extended region on chromosome 1q32 (Chr1 locus) and the age-related maculopathy susceptibility 2/high-temperature requirement factor A1 (ARMS2/HTRA1), 2 tightly linked genes located on chromosome 10q26 (Chr10 locus).10,11,12,13,14 Other common AMD-associated loci (excluding rare variants) are not nearly as penetrant. The gene discussed is HTRA1; the disease is age-related macular degeneration.