This association study in individuals of European descent investigated variants associated with age-related macular degeneration and first reported the protective effect for the R32Q allele. Affected individuals consisted of unrelated individuals with clinically documented AMD, while controls did not show any distinguishing signs of macular disease and had no family history of the disease. The first cohort had highly significant numbers, 44/1096 case alleles vs. 61/550 control alleles (case+: 44, case-: 1,052, cont+: 61, cont-: 489). This produces an odds ratio of 0.335 and p = 9 * 10^-9.
This is reported to be replicated in a second cohort, but it’s unclear what the numbers from this cohort are — table 2 supposedly combines numbers from both, but the number of controls for R32Q in table 2 (269 controls, 538 alleles) is less than the number of controls in table 1 (275 controls, 550 alleles) but more than the number of control individuals the text describes for the second cohort (114 controls, 228 alleles).
Although they do not report specific numbers, the authors cite statistically significant results for both homozygous and heterozygous individuals and propose a codominant effect.