GDNF and renal agenesis: However, apart from a higher occurrence of unilateral renal agenesis in heterozygous Gdnf knock-out mice, the reduction of nephron numbers also leads to development of a specific pattern of glomerular alterations, such as glomerular hypertrophy with hyperplasia of endothelial and mesangial glomerular cells and thickening of the glomerular basement membrane (GBM), predisposing the mice to development of glomerular sclerosis [43].