Introduction:
Adult polycystic kidney disease is a hereditary disorder. It is also known as "Autosomal dominant polycystic disease”. It consists of multiple cysts in the kidney that gradually are gradually expanding. Ultimately the expanding cysts destroy the renal parenchyma (functional tissue) and leads to renal failure. It occurs in both kidneys (bilateral). Since it affects only minority of the nephrons (functional units of kidney) in the beginning, renal function is retained until the fourth or fifth decade of life when the cysts have significantly expanded.
Genetics:
It occurs due to wide range of mutation in PKD1 and PKD2 genes. The PKD1 gene is located on chromosome 16p13.3 and encodes a large (460-kD) integral membrane protein called polycystin-1. It contains domains that are usually involved in cell-cell and cell-matrix interactions. The PKD2 gene is located on chromosome 4q21. Its product is an integral membrane protein named polycystin-2 that is expressed in all segments of the renal tubules. Polycystin-2 functions as a Ca2+-permeable cation channel. Mutations in PKD1 is seen in about 85% of cases.
Morphology:
Both kidneys become enlarged, external surface appears to be entirely composed of a mass of cysts. Grossly no intervening parenchyma is seen between the cysts however microscopically functioning nephrons are seen dispersed between the cysts. The cysts may contain clear, turbid, red or brown fluid.
Clinical Features:
Many patients remain asymptomatic until renal insufficiency develops. Enlarged kidneys are usually palpable and may cause a dragging sensation. Less common presentations may include pain, hematuria, polyuria and hypertension. Patients also tend to have extrarenal congenital anomalies like polycystic liver disease. Less frequently cysts may be also occur in the spleen, pancreas, and lungs. Patients may survive for many years with azotemia.
Adult polycystic kidney disease is a hereditary disorder. It is also known as "Autosomal dominant polycystic disease”. It consists of multiple cysts in the kidney that gradually are gradually expanding. Ultimately the expanding cysts destroy the renal parenchyma (functional tissue) and leads to renal failure. It occurs in both kidneys (bilateral). Since it affects only minority of the nephrons (functional units of kidney) in the beginning, renal function is retained until the fourth or fifth decade of life when the cysts have significantly expanded.
Genetics:
It occurs due to wide range of mutation in PKD1 and PKD2 genes. The PKD1 gene is located on chromosome 16p13.3 and encodes a large (460-kD) integral membrane protein called polycystin-1. It contains domains that are usually involved in cell-cell and cell-matrix interactions. The PKD2 gene is located on chromosome 4q21. Its product is an integral membrane protein named polycystin-2 that is expressed in all segments of the renal tubules. Polycystin-2 functions as a Ca2+-permeable cation channel. Mutations in PKD1 is seen in about 85% of cases.
Morphology:
Both kidneys become enlarged, external surface appears to be entirely composed of a mass of cysts. Grossly no intervening parenchyma is seen between the cysts however microscopically functioning nephrons are seen dispersed between the cysts. The cysts may contain clear, turbid, red or brown fluid.
Clinical Features:
Many patients remain asymptomatic until renal insufficiency develops. Enlarged kidneys are usually palpable and may cause a dragging sensation. Less common presentations may include pain, hematuria, polyuria and hypertension. Patients also tend to have extrarenal congenital anomalies like polycystic liver disease. Less frequently cysts may be also occur in the spleen, pancreas, and lungs. Patients may survive for many years with azotemia.