WT1 and Denys-Drash syndrome: Most of these studies have investigated expression in fresh human tissue, and most studies have found the VEGF-Axxxb mRNA to be downregulated in pathological conditions such as cancer [7], diabetic retinopathy [6], Denys Drash Syndrome (a condition caused by a mutation of the tumour suppressor gene WT1) [8], and retinal vein occlusion [9].