What is Polycystic Kidney Disease (PKD)?
Polycystic Kidney Disease (PKD) is a range of inherited conditions that cause renal (kidney) failure, injury to other organs and sometimes result in premature death in children and adults. PKD is characterised by the development of multiple micro and macroscopic cysts – sacs filled with fluid – throughout both kidneys and often, the liver.
There are 2 major forms of polycystic kidney disease:
- ADPKD or autosomal dominant polycystic kidney disease
- ARPKD or autosomal recessive polycystic kidney disease
Both types of PKD occur from abnormalities or mutations in single genes inside human cells. Genes contain DNA, the ‘building blocks’ of life which contain instructions for making the proteins that are necessary for human development. When there is a genetic mutation, the proteins don’t work properly or are sometimes missed. In PKD, the genetic mutations affect the kidneys primarily, but also affect the development of the liver and other organs.
The genes are packed into 23 pairs of 46 chromosomes. One of each pair is inherited from each parent, along with any mutations.
PKD disorders are called ‘autosomal’ because the mutations occur in one or more of the 22 chromosomal sets that are ‘non-sex’. (The 23rd pair are the XY chromosomes that determine gender.) PKD occurs equally in men and women with no gender or ethnic bias.
ADPKD is the world’s most common inherited kidney disease, in which fluid-filled cysts develop, multiply and grow in both kidneys. Other organs, such as the liver and brain, may be affected.
Over 12.5 million adults and children worldwide have ADPKD. It is chronic, progressive and incurable. Over half of those affected will have kidney failure by the time they are 60 years old. Many will experience regular pain, disabiity and anxiety throughout life.
ARPKD is a rare form of polycystic kidney disease affecting 1 in 20,000 live births worldwide. It can cause both kidney failure at an early age. In some cases, the liver is affected and this is known as congenital hepatic fibrosis (CHF).
ARPKD is chronic, incurable and can progress rapidly. During pregnancy and at birth, it can be severe and life-threatening, however the prognosis for children born with ARPKD has improved significantly over the past years.