,15 Notably, about 10% of patients with atypical or “class 2” cyst distributions, described as unilateral, segmental, asymmetric, lopsided, or with atrophy, were excluded from the Mayo Clinic classification, but have a mild prognosis and are less likely to have a pathogenic PKD1 or PKD2 variant.16 This evidence concerns the gene PKD1 and cyst.