Purpose: To genetically characterize a subphenotype of geographic atrophy (GA) in AMD associated with rapid progression and a diffuse-trickling appearance on fundus autofluorescence imaging. Methods: Patients from the Fundus Autofluorescence in Age-Related Macular Degeneration Study were phenotyped for diffuse-trickling GA (dt-GA; n = 44). DNA was analyzed for 10 known AMD-associated genetic variants. A genetic risk score (GRS) was calculated and compared with patients with nondiffuse-trickling GA (ndt-GA; n = 311) and individuals from the 1000 genomes project (1000G; n = 267). Given the phenotypic overlap between diffuse-trickling and late-onset retinal degeneration (LORD), all C1QTNF5 exons and their exon/intron boundaries were sequenced. Results: A statistically significant difference in allele frequencies between dt-GA and ndt-GA were found for CFH:rs1061170 and CFH:rs800292 (Pcorrected = 0.03). The ARMS2 variant rs10490924 was significantly more frequent in dt-GA than in 1000G individuals (Pcorrected