Mann-Whitney tests showed men and women with SCD did not differ in education level (W = 6814.0, p = 0.83), number of APOE ε4 carriers (W = 6990.0, p = 0.62), or age (W = 7455.5, p = 0.67) (see Table 2). This evidence concerns the gene APOE and Schnyder corneal dystrophy.