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 diffusetrickling 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 < 0.01). The GRS of dt-GA patients was in-between the score of the 1000G individuals and that of patients with ndt-GA, significantly differing from both (Pcorrected <0.01). Sequencing of C1QTNF5 revealed 28 unique variants although none showed a statistically significant association with dt-GA when compared with 1000G individuals. CONCLUSIONS. The dt-GA phenotype shows a remarkably different genetic risk profile from other GA phenotypes secondary to AMD. Disease-associated C1QTNF5 mutations were not identified. Together, these results suggest that the dt-GA phenotype is associated with a genetic background substantially different from other GA phenotypes and underlines the necessity to refine the clinical phenotyping, specifically when aiming for individualized therapies in AMD.
Supported by grants by the Deutsche Forschungsgemeinschaft (DFG-Germany Research Foundation, Bonn, Germany): Ho1926/3-1 (FGH), FL 658/4-1 (MF), and WE 1259/19-2 (BHFW), and the BONFOR program of the University of Bonn: O-137.0020 (ML; Bonn, Germany).
- C1QTNF5 gene
- Diffuse-trickling phenotype
- Fundus autofluorescence imaging
- Genetic risk factors
- Late-onset retinal degeneration