Autosomal recessive polycystic kidney disease (ARPKD) is a rare genetic childhood condition. Cysts grow in the kidneys and damage them. In some cases, the liver can also be damaged.
The symptoms of ARPKD range from moderate to life-threatening, and include:
The sooner the symptoms of ARPKD develop in a child's life, the more severe they usually are (see below).
Read more about the symptoms of autosomal recessive polycystic kidney disease.
The kidneys
The kidneys are two bean-shaped organs located on either side of the body, just beneath the ribcage. The main role of the kidneys is to filter out waste products from the blood before passing them out of the body as urine. The kidneys also help to maintain blood pressure at a healthy level.
Treatment
There is currently no cure for ARPKD.
Treatment focuses on the condition's associated symptoms and any complications that may occur, such as kidney disease and high blood pressure.
In severe cases of ARPKD, symptoms may be present before birth or at birth and the newborn baby will usually need to be admitted to an intensive care unit so their breathing can be assisted with a ventilator.
Sadly in the most severe cases, despite the best standard of care, there is a significant risk that the baby will die in the first few weeks after birth.
Older children with ARPKD may lose all of their kidney function (end-stage chronic kidney disease, or kidney failure).
If kidney failure does occur, there are two possible treatments:
Read more about the treatment of autosomal recessive polycystic kidney disease.
Early stages of ARPKD
ARPKD can be classified according to when symptoms develop and cause problems. The earlier symptoms develop the poorer the outlook
- Before birth: symptoms develop before birth and the baby is born with seriously underdeveloped lungs. Around three out of four babies born with this type of ARPKD will die within a week of birth, usually from breathing difficulties
- In infancy: symptoms develop in the first month after birth. This type of ARPKD usually leads to kidney failure, which requires dialysis
- In childhood: most common symptoms are high blood pressure, chronic kidney disease and liver disease
As ARPKD is so rare, it is difficult to accurately estimate which type of the condition is the most common.
Note that members of the same family can often be born with different categories of the condition at different stages. It is not clear why this is the case.
Causes
ARPKD is caused by a genetic mutation in the PKHD1 gene. The PKHD1 gene instructs the cell on how to make the protein called fibrocystin, found in various cells of the body including the kidneys, liver and lungs. When a genetic mutation occurs, it causes instructions to the cell to become 'scrambled', or for parts to be missing, so that the protein is not made properly and cannot perform its normal function. The PKHD1 mutation disrupts normal development of the kidneys and in some cases, the liver, causing cyst development and scar formation.
ARPKD is an autosomal recessive disease, which means both copies of the PKHD1 gene have to be mutated for the disease to develop. If there is one faulty copy of the gene, a person carries the mutation without developing any symptoms. However, if two people who are both carriers have a baby, there is a one in four chance the baby will develop ARPKD.
Read more about the causes of autosomal recessive polycystic kidney disease.
Who is affected
ARPKD is a rare condition. It is estimated that one in 20,000 babies is born with the condition.