a shows box plots (and corresponding data points) of FHR-4 levels measured in two separate AMD cohorts: Cambridge (plasma from 214 controls and 304 late AMD cases) and EUGENDA (serum from 308 controls and 180 late AMD cases). AMD patients show statistically significantly elevated FHR-4 levels compared to controls. Geometric mean FHR-4 levels were: Cambridge, 5.5 µg ml−1 in controls vs. 6.6 µg ml−1 in cases; EUGENDA, 6.0 µg ml−1 in controls vs. 7.2 µg ml−1 in cases. These differences remained significant after adjustment for sex, age, batch effects and first two genetic principal components (P value = 0.018 and 8.4 × 10−5 for Cambridge and EUGENDA, respectively; Wald test). b shows box plots (and corresponding data points) of FH levels measured in the same samples, where no statistically significant difference between cases and controls was observed: Cambridge, 349.0 µg ml−1 in controls vs. 348.6 µg ml−1 in cases; EUGENDA, 304.7 µg ml−1 in controls vs. 308.7 µg ml−1 in cases. Each box plot depicts median value (central line), first quartile (lower bound line) and third quartile (upper bound line). Source data are provided as a Source Data file.