Patients with atypical polycystic kidney disease by imaging were older (55 versus 43 years, P < 0.001) with a male predominance (63.0% vs. 43.8%, P = 0.01); they were less likely to have a family history of ADPKD (26.1% vs. 74.6%, P < 0.001) or a detectable PKD1 or PKD2 mutation (9.2% vs. 80.4%, P < 0.001; Fig. 2a). The gene discussed is PKD2; the disease is autosomal dominant polycystic kidney disease.