Genetics

PKD usually runs in families

Genetics of Autosomal Dominant Polycystic Kidney Disease:

Approximately 85 percent of families with autosomal dominant polycystic kidney disease (ADPKD) have a mutation in the PKD1 gene, located on chromosome 16; these people have PKD1 disease. The remaining 15 percent have a mutation in the PKD2 gene on chromosome 4; this is called PKD2 disease.

In some cases, it is not possible to detect which gene is mutated. PKD2 disease is milder; therefore, it often presents later in life and is sometimes not diagnosed at all. Thus, it is likely that more than 15 percent of all people with ADPKD have PKD2 disease.

Kidney failure occurs at an earlier age in PKD1 patients; the average age of end-stage renal disease (that is, needing dialysis or a transplant) is approximately 55 years in PKD1 versus 74 years in PKD2 patients.

In approximately 15 percent of cases, ADPKD occurs in people without a family history of the disease (ie, family members have been evaluated and have no evidence for PKD). This is due to the patient having a new (de novo) genetic mutation that was not present in either parent.

Genetics of Autosomal Recessive Polycystic Kidney Disease:

Mutation of the PKHD1 gene — Autosomal recessive polycystic kidney disease (ARPKD) is caused by mutations in the PKHD1 gene located on chromosome 6, which encodes fibrocystin (also referred to as polyductin), a large protein. Although the function of fibrocystin is currently unknown, it is found in different parts of the ducts in the kidney, in some parts of the bile ducts in the liver, and also in the pancreas and lungs.

The largest database for PKHD1 mutations contains more than 750 different mutations. Most patients with ARPKD are compound heterozygotes, who carry two different mutant alleles.

If you have polycystic kidney disease and you're considering having children, a genetic counselor can help you assess your risk of passing the disease to your offspring.

Disclaimer: The UCLA Health System cannot guarantee the accuracy of such information. The information is provided without warranty or guarantee of any kind. Please speak to your Physician before making any changes.