CDKN2A and Schnyder corneal dystrophy: The mean difference in p16 expression between the SCD participants on CTT and comparators was 1.3 log2 p16 units (10.0 vs. 8.7 log2 p16 units, p = 0.002), while the difference between the SCD participants not on CTT and comparators was 1.4 (10.1 vs. 8.7 log2 p16 units, p = 0.001) (Figure 1B).