APOE and Schnyder corneal dystrophy: Another multicenter study of 1640 persons with SCD found that beyond the large variability in the frequency of amyloid positivity between cohorts (10–76%), age, settings, APOE-ε4 carriership and SCD-specific characteristics may facilitate the identification of amyloid-positive individuals, which is consistent with the definition of SCD-plus (Janssen et al. 2021).