CDKN2A and Schnyder corneal dystrophy: There are several potential explanations for these findings: (1) This study was underpowered to detect these associations, (2) the p16 expression observed is a predictive marker of future morbidity and thereby may be more suitable for a longitudinal cohort, or most likely (3) the widespread impact and burden of SCD on cellular senescence itself may be greater than these various markers of clinical severity, which often does not capture disease severity in SCD, which is poorly defined [21].