To examine the impact of the ARMS2/HTRA1 genotype on the rate of GA enlargement, Tiarnán Keenan, MD, PhD, and colleagues analyzed data from the Age-Related Eye Disease Study 2 (AREDS2) clinical trial, which included 546 eyes from 406 participants (mean age, 73.8). Published in Ophthalmology, the study found that GA enlargement occurred faster in eyes with ARMS2 risk alleles. The rate of enlargement varied with genotype: 0.224 mm/year for zero to two risk alleles, 0.298 mm/year for one to two risk alleles, and 0.317 mm/year for two risk alleles. However, this relationship depended on the baseline GA area. In eyes with small GA areas, ARMS2 risk alleles significantly accelerated enlargement. In eyes with moderately small or medium/large GA areas, genotype had no significant impact on enlargement. Furthermore, ARMS2 genotype affected enlargement in nonmultifocal GA but not progression to multifocal GA. “These findings may explain some discrepancies between previous studies and have implications for both research and clinical practice,” wrote Dr. Keenan and colleagues.