Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common, life-threatening inherited human disorders and the most common hereditary kidney disease. It is associated with large interfamilial and intrafamilial variability, which can be explained to a large extent by its genetic heterogeneity and modifier genes. It is also the most common of the inherited cystic kidney diseases — a group of disorders with related but distinct pathogenesis, characterized by the development of renal cysts and various extrarenal manifestations, which in case of ADPKD include cysts in other organs, such as the liver, seminal vesicles, pancreas, and arachnoid membrane, as well as other abnormalities, such as intracranial aneurysms and dolichoectasias, aortic root dilatation and aneurysms, mitral valve prolapse, and abdominal wall hernias. Over 50% of patients with ADPKD eventually develop end stage kidney disease and require dialysis or kidney transplantation. ADPKD is estimated to affect at least one in every 1000 individuals worldwide, making this disease the most common inherited kidney disorder with a diagnosed prevalence of 1:2000 and incidence of 1:3000-1:8000 in a global scale. Signs and symptoms Among the clinical presentation are: Acute loin pain Blood in the urine Ballotable kidneys Subarachnoid hemorrhage (berry aneurysm) Hypertension Associated liver cysts Uremia due to kidney failure Anemia due to chronic kidney disease Increase RBC or erythropoietin secretion Signs and symptoms of ADPKD often develop between 30 and 40 years of age. Genetics ADPKD is genetically heterogeneous with two genes identified: PKD1 (chromosome region 16p13.3; around 85% cases) and PKD2 (4q21; around 15% cases). Several genetic mechanisms probably contribute to the phenotypic expression of the disease. Although evidence exists for a two-hit mechanism (germline and somatic inactivation of two PKD alleles) explaining the focal development of renal and hepatic cysts, haploinsufficiency is more likely to account for the vascular manifestations of the disease. Additionally, new mouse models homozygous for PKD1 hypomorphic alleles 22 and 23 and the demonstration of increased renal epithelial cell proliferation in PKD2 +/− mice suggest that mechanisms other than the two-hit hypothesis also contribute to the cystic phenotype. Large interfamilial and intrafamilial variability occurs in ADPKD. Most individuals with PKD1 mutations have kidney failure by age 70 years, whereas more than 50% of individuals with PKD2 mutations have adequate renal function at that age (mean age of onset of end-stage renal disease: 54·3 years with PKD1; 74·0 years with PKD2). The significant intrafamilial variability observed in