Among the ten patients without any class 3–5 PKD1/2 findings, we identified three alternative molecular diagnoses: ARPKD (MIM 263200), ALG9-associated PKD, and Birt–Hogg–Dubé syndrome (BHDS, MIM 135150) (Table 1, Fig. 4). Here, PKD1 is linked to autosomal recessive polycystic kidney disease.