Polycystic Kidney Disease | Anatomy2Medicine
Polycystic Kidney Disease Symptoms

Polycystic Kidney Disease

    • Autosomal-dominant (adult) polycystic kidney disease (ADPKD)
      • characterized by multiple expanding cysts of both kidneys that ultimately destroy the renal parenchyma
      • cause renal failure. (MCQ)
      • autosomal dominant with high penetrance.
      • Despite the autosomal dominant inheritance, the manifestation of the disease requires mutation of both alleles of either PKD gene
      • universally bilateral
      • cysts initially involve only portions of the nephrons, so renal function is retained until about the fourth or fifth decade of life.
      • genetically heterogeneous
      • caused by mutations in genes located on
  • chromosome 16p13.3 (PKD1) (Most common) (MCQ)
        • chromosome 4q21 (PKD2),
      • Mutations of PKD1 (MCQ)
        • account for about 85% of cases
        • associated with a more severe disease, end-stage renal disease or death
  • Genetics and Pathogenesis.
  • PKD1 gene
          • encodes a large (460-kD) integral membrane protein named polycystin-1, (MCQ)
          • localized to tubular epithelial cells, particularly those of the distal nephron. (MCQ)
        • PKD2 gene
          • product polycystin-2 is an integral membrane protein.
          • localized to all segments of the renal tubules and is also expressed in many extrarenal tissues. (MCQ)
  • functions as a Ca2+-permeable cation channel
  • a basic defect in ADPKD is a disruption in the regulation of intracellular Ca2+ levels. (MCQ)
  • Morphology.
      • microscopic examination reveals functioning nephrons dispersed between the cysts.
      • cysts arise from the tubules throughout the nephron
  • Extrarenal congenital anomalies.
    • About 40% have one to several cysts in the liver (polycystic liver disease) that are usually asymptomatic. (MCQ)
      • cysts are derived from biliary epithelium.
      • Cysts occur much less frequently in the spleen, pancreas, and lungs.
    • Intracranial berry aneurysms arise in the circle of Willis(MCQ)
    • subarachnoid hemorrhages (MCQ)
    • Mitral valve prolapse (MCQ)
  • chronic renal failure is remarkable in that patients may survive for many years with azotemia slowly progressing to uremia(MCQ)
  • about 40% of adult patients die of coronary or hypertensive heart disease, (MCQ)
  • Autosomal-recessive (childhood) polycystic kidney disease (ARPKD)
          • Perinatal, neonatal type are the most common(MCQ)
          • serious manifestations are usually present at birth
  • young infant might succumb rapidly to renal failure.
          • most common mutations are due to  PKHD1 gene
      • maps to chromosome region 6p21–p23. (MCQ)
      • encodes a large novel protein, fibrocystin(MCQ)
  • Morphology.
      • Dilated elongated channels are present at right angles to the cortical surface, completely replacing the medulla and cortex
      • saccular dilation of all collecting tubules. (MCQ)
  • cysts have a uniform lining of cuboidal cells, reflecting their origin from the collecting ductS
    • In almost all cases the liver has cysts associated with portal fibrosis  and proliferation of portal bile ducts.
    • Patients who survive infancy (infantile and juvenile forms) may develop a peculiar type of hepatic fibrosis ,termed congenital hepatic fibrosis. (MCQ)