Polycystic kidney disease is caused by a genetic fault that disrupts the normal development of some of the cells in the kidneys and causes cysts to grow.
Abnormal genes cause polycystic kidney disease, and the genetic defects mean the disease runs in families. Rarely, a genetic mutation can be the cause of polycystic kidney disease.
There are two types of polycystic kidney disease, caused by different genetic flaws:
Autosomal dominant polycystic kidney disease (ADPKD).
ADPKD is caused by a genetic fault that disrupts the normal development of some of the cells in the kidneys and causes cysts to grow.
Faults in one of two different genes are known to cause ADPKD. The affected genes are:
PKD1 – which accounts for 85% of cases
PKD2 – which accounts for 15% of cases
Both types of ADPKD have the same symptoms, but they tend to be more severe in PKD1.
A child has a one in two (50%) chance of developing ADPKD if one of their parents has the faulty PKD1 or PKD2 gene.
Signs and symptoms of ADPKD often develop between the ages of 30 and 40. In the past, this type was called adult polycystic kidney disease, but children can develop the disorder.
Only one parent needs to have the disease in order for it to pass along to the children. If one parent has ADPKD, each child has a 50 percent chance of getting the disease. This form accounts for about 90 percent of cases of polycystic kidney disease.
Autosomal recessive polycystic kidney disease (ARPKD).
This type is far less common than is ADPKD. The signs and symptoms often appear shortly after birth. Sometimes, symptoms don't appear until later in childhood or during adolescence.
Both parents must have abnormal genes to pass on this form of the disease. If both parents carry a gene for this disorder, each child has a 25 percent chance of getting the disease.
Non-inherited Autosomal dominant polycystic kidney disease.
In around one in four (25%) cases, a person develops ADPKD without having a known family history of the condition.
This could be because the condition was never diagnosed in a relative, or a relative with the condition may have died before their symptoms were recognised.
In around one in 10 cases of ADPKD, the mutation develops for the first time in the affected person. It's not known what causes this to happen.