PKD1 and cyst: Consistent with the condition's autosomal dominant mode of inheritance, patients generally carry one wild type and one mutant allele of PKD1 or PKD2. While the mechanisms that initiate cyst formation remain the subject of investigation and debate, there is strong evidence that the stochastic acquisition of “second hit” mutations in the wild type PKD1 or PKD2 allele can play an important role in catalyzing the processes that lead to cyst development (3–5).