Plasma PNP levels were markedly elevated in the patients compared to controls (SCD: 2772 ± 362 vs. CON: 1310 ± 188.1 pg/mL, p = 0.001, Figure 1A) and those with severe disease had higher PNP levels (Severe: 3558 ± 570.9 vs. Mild: 1681 ± 240.9 pg/mL, p = 0.003, Figure 1B) and LDH levels (Severe: 373 ± 21.0 U/L vs. Mild: 249.6 ± 14.0 U/L, p < 0.0001, Figure 1C) than those with mild disease. This evidence concerns the gene PNP and Schnyder corneal dystrophy.