PIWIL4 and Schnyder corneal dystrophy: Calculating the differences between the amounts of DDX4+ cells (Figure 6g) and PIWIL4+ cells (Figure 6h) at the individual patient level, a gap can be seen (Figure 6i): The patient with SCD and the patient with MDS are displaying almost the same amount of DDX4+ cells as PIWIL4+ SPG, hinting at a germ cell composition of mainly undifferentiated SPG.