ARPKD is disease caused by a mutation in a kidney building block protein called fibrocystin. The gene for this is named PKHD1. It is the only gene known to cause this particular problem, and a mutation in this gene is found in up to 90% of people with ARPKD. The mutation causes abnormal fluid filled cysts to be formed in the kidney tissue. As these cysts grow in number and size, they press on other parts of the kidney, causing damage and scarring. Children can be born with severely enlarged kidneys (the size of normal adult kidneys) and can have immediate kidney failure at birth, or the kidneys can be enlarged and working normally at birth, then progress over the next several years to worse kidney disease and kidney failure. Over half of children born with this will have kidney failure by the age of 10. High blood pressure is often a problem. Some children with particularly severe forms may be born with lungs that are too small for them to breath on there own. Some of these children may die in early infancy.
The disease also affects other parts of the body besides the kidney, most importantly the liver. Cysts and scarring of the liver may be a problem from early childhood, and may be the most severe problem in some children with ARPKD.
ARPKD is found in 1:20,000 – 1:40,000 newborns. Right now there are no specific cures for this disease.
How does genetic testing help?
Sometimes it is difficult to be sure a child has ARPKD. A few other diseases can look the same in a newborn child, and mild forms of the disease may not show up until later in childhood , and then may show up first by affecting the liver. A genetic test can confirm the presence of a mutation in the PKHD1 genes and confirm that the problem is ARPKD and not some other kidney problem that would need different monitoring or treatment.
Once a mutation in the PKHD1 gene is found in a family, then decisions can be made whether testing other family members would be helpful. In general, testing of other children who do not appear to have any problems is not suggested for rare, autosomal recessive genes.
Other information can be found at:
- PKD Foundation http://www.pkdcure.org/site/PageServer
- Gene Tests http://www.genetests.org/
