ARPKD is caused by a DNA mutation (abnormality) in a gene called PKHD1, which produces a protein called fibrocystin that gives the 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 can also cause enlargement and scarring of the liver, or the bile 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 ducts become more vulnerable to infection.
The genetic fault responsible for ARPKD is usually passed on to a child by their parents.
The mutation that causes ARPKD is known as an autosomal recessive mutation.
This means that a baby needs to receive 2 copies of the mutated gene to develop the condition: 1 from their mother and 1 from their father.
If a baby only receives 1 copy of the mutated gene from 1 of their parents, he or she will not develop ARPKD, but will carry the mutated gene.
It's estimated that 1 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:
- 1 in 4 chance the baby will receive a pair of normal genes
- 1 in 2 chance the baby will receive 1 normal gene and 1 mutated gene, and become a carrier of the PKHD1 mutation
- 1 in 4 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.