PKD1 and autosomal dominant polycystic kidney disease: We propose the possibility that mitochondrial abnormalities accumulate in tubular cells of patients with ADPKD carrying heterozygous PKD1 mutations because of decreased intracellular Ca2+ levels and that excessive superoxide from abnormal mitochondria in the kidneys of patients with ADPKD causes DNA damage, which includes second mutation of PKD-related genes.