Causes

Autosomal recessive polycystic kidney disease (ARPKD) is an inherited condition, which means it's passed on to a child from their parents.

ARPKD is caused by aDNA mutation (abnormality) ina gene called PKHD1, which produces a protein called fibrocystin that givesthe kidney its structure.The faulty PKHD1 gene is responsible for small fluid-filled sacs (cysts) and scarring developing in the kidneys.

In some cases, the faulty gene canalso cause enlargement and scarring of the liver, or thebile ducts(which produce a digestive fluid called bile) to widen. This can make it difficult for blood to flow through the liver and the bile ductsbecome more vulnerable to infection.

The genetic fault responsible for ARPKD is usually passed on to a child by their parents.

How ARPKD is inherited

The mutation that causes ARPKD is known as an autosomal recessive mutation.This means thata baby needs to receive two copies of the mutated gene to develop the condition one from their mother and one fromtheir father.

If a baby only receives one copy of the mutated gene from one oftheir parents, he or she won't develop ARPKD, but will carry the mutated gene. It's estimated that1 in 70 people in the UK is a carrier of the mutated PKHD1 gene.

If you're a carrier of the mutated gene and you conceive a baby with a partner who's also a carrier, there's a:

• 25% chance the baby will receive a pair of normal genes
• 50% chance the baby will receive one normal gene and one mutated gene, and become a carrier of the PKHD1 mutation
• 25% chance the baby will receive a pair of mutated genes and develop ARPKD

If you have a family history of ARPKD and you're considering trying for a baby, your GP may refer you to a geneticist or genetic counsellor to discuss the risks, benefits and limitations of testing for the condition.

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