Analyzing kidney/body weight and cystic index between P19 and P21 in a set of 46 cre positive Pkd1cko/cko animals (8 Hnf4αcko/cko; 23 Hnf4αcko/wt; 15 Hnf4αwt/wt), our results suggest that the presence of HNF4α has a significant protective effect on cyst formation (Figure 5). The gene discussed is HNF4A; the disease is cyst.