Introduction

Autosomal dominant polycystic kidney disease (ADPKD) is an inherited condition that causes small, fluid-filled sacs called cysts to develop in the kidneys.

Although children affected by ADPKD are born with the condition, it rarely causes any noticeable problems until the cysts grow large enough to affect the kidneys' functions.

In most cases, this doesn't occur until a person is between 30 and 60 years of age.Less commonly, children or older people may have noticeable symptoms as a result of ADPKD.

When ADPKD reaches this stage, it can cause a wide range of problems, including:

• abdominal (tummy) pain
• high blood pressure (hypertension)
• blood in the urine (haematuria) which may not always be noticeable to the naked eye
• potentially serious upper urinary tract infections (UTIs)
• kidney stones

Kidney function will gradually deteriorate until so much is lost that kidney failure occurs.

The affected genesare:

• 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 inPKD1.

A child has aone in two (50%) chance of developing ADPKD if one of their parents has the faultyPKD1 or PKD2 gene.

Autosomal recessive polycystic kidney disease (ARPKD) is a rarer type of kidney disease which can only be inherited if both parents carry the faulty gene and in this type problems usually start much earlier, during childhood.

Non-inherited ADPKD

In around one in four (25%) cases, a person develops ADPKD without having a knownfamily 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 ofADPKD, the mutation develops for the first time in the affected person. It's not known what causes this to happen.

The affected person can pass the faulty gene on to their children in the same way as someone who's inherited it from a parent (see above).

Who's affected

ADPKD is the most commoninherited condition to affect the kidneys, although it's still relatively uncommon.

Only around one or two in every 1,000 people are born with ADPKD, which means there are currently around 60,000 people in the UK with the condition.

Treating ADPKD

There's currently no cure for ADPKD, but various treatments are available to manage problems caused by the condition.

Most problems such as high blood pressure, pain and UTIs can be treated with medication, although you may need to have an operation to remove anylarge kidney stones that develop.

If the condition reaches a point where the kidneys aren't able to function properly, there are two main treatment options:

• dialysis where a machine is used to replicate kidney functions
• kidney transplant where a healthy kidney is removed from a living or recently deceased donor and implanted into someone with kidney failure

In some cases of ADPKD in adults (where chronic kidney disease is advanced and progressing rapidly), a medication called tolvaptan can be used to slow down the formation of cysts and protect kidney function.

Some people experience kidney failure soon after the condition is diagnosed, whereas othersmay live the rest of their life with their kidneys working relatively well.

On average, around half of people with ADPKD require treatment for kidney failure by the time they're 60.

As well askidney failure, ADPKD can also cause a number of other potentially serious problems, such as heart attacks and strokes caused by high blood pressure, or bleeding onthe brain ( subarachnoid haemorrhage ) caused by a bulge in the wall ofa blood vessel in the brain ( brain aneurysm ).

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