MCDK was thought to be a nonhereditary renal disease, but in recent years, a human HNF1B gene mutation was found to have a causal relationship with a renal developmental defect accounting for 10–30% of all cases of kidney and urinary tract congenital abnormalities (CAKUT) [40], MCDK, and autosomal dominant tubulointerstitial kidney disease (ADTKD) [41]; 1 in 10 patients with unilateral MCDK are reported to have an HNF1B gene mutation [42]. The gene discussed is HNF1B; the disease is autosomal dominant medullary cystic kidney disease with or without hyperuricemia.