Authors: William M Bennett, MD, Frederic F Rahbari-Oskoui, MD, MSCR, Arlene B Chapman, MD | Content provided by UpToDate.com.
Normally, the kidneys filter out excess toxic and waste substances and fluid from the blood. In people with polycystic kidney disease (PKD), the kidneys become enlarged with cysts that impair normal kidney function. This can sometimes lead to kidney (renal) failure and the need for dialysis or kidney transplantation.
There are two major forms of PKD: autosomal dominant polycystic kidney disease (ADPKD) and autosomal recessive polycystic kidney disease (ARPKD).
ADPKD is the most common hereditary kidney disease, occurring in approximately 1 in every 400 to 1000 people. Autosomal dominant means that each child of an affected parent has a 50 percent chance of inheriting the disease. In addition, autosomal dominant means that it does not skip a generation (ie, if a patient with the disease does not pass it along to one of his or her children, then the disease disappears from that family and grandchildren cannot inherit the disease). However, some patients with ADPKD are not diagnosed during their lifetimes, due to very few symptoms. This means that a family member may have the disease without knowing it.
ARPKD is uncommon and is typically diagnosed in infancy or in utero, although less severe forms may be diagnosed later in childhood or adolescence. The estimated incidence is approximately 1 in 20,000 people. Autosomal recessive means that the mutated gene must be present in both parents, who, because they carry only one abnormal gene, are considered carriers. When both parents are carriers (each having one abnormal and one normal gene), there is a 25 percent chance that each child will inherit an abnormal gene from both parents and have the disease.