Autosomal Dominant Polycystic Kidney Disease
Humans normally have a total of 46 chromosomes (which are tiny, DNA-containing elements) that are present in every cell of the body. DNA encodes genes, which specify all the proteins that make up the body and control its functions.
In humans, there are 23 pairs of chromosomes in cells; one pair is inherited from each parent at conception. Each cell contains 22 pairs of chromosomes called autosomes, which are the same in males and females. The remaining pair of chromosomes, the X and Y chromosomes, is not shaped similarly, so it is not matched in the same way as the autosomes.
A genetic disease occurs when one or both parents pass abnormal genes to a child at conception. An "autosomal dominant" genetic disease occurs when only one defective gene is necessary to cause the disease. Either the mother or father can pass it along.
Mutations in the PKD1 and PKD2 genes cause autosomal dominant polycystic kidney disease.
The PKD1 gene is located on chromosome 16; the PKD2 gene is located on chromosome 4. The functions of the proteins made by these genes are not fully understood, but it is known that they are involved in transmitting chemical signals from outside the cell to the cell's nucleus. Researchers believe that the two proteins work together to promote normal kidney development and function.
Mutations in the PKD1 or PKD2 gene lead to the formation of thousands of cysts, which disrupt the normal functions of the kidneys and other organs. People with mutations in the PKD2 gene typically have a less severe form of autosomal dominant polycystic kidney disease than people with PKD1 mutations.
For a person with autosomal dominant polycystic kidney disease, there is a 50 percent chance that the disease will be passed to a child. In about 25 percent of cases, an individual with autosomal dominant polycystic kidney disease does not have a parent with the disorder.