Autosomal Recessive Polycystic Kidney disease
Autosomal Recessive Polycystic Kidney disease (ARPKD) is a genetic condition. In almost all children with the condition, it is possible to identify a mutation in a gene called PKHD1, which codes for a protein called fibrocystin.
Medical text written November 2011 by Dr A Saggar, Consultant in Clinical Genetics and General Medicine, St George’s Hospital Medical School, London, UK.
ARPKD is characterised by enlarged kidneys, which may or may not have cysts and hypertension (high blood pressure). A total of 30 to 50 per cent of babies with ARPKD die shortly after birth, mainly because of underdeveloped lungs. The outlook for babies that survive the first four weeks improves dramatically. Although reduced kidney function (renal impairment) can occur during the first four weeks of life, it is not usually a cause of death in this period.
A baby born with ARPKD may have the following problems:
- enlarged abdomen due to larger than normal kidneys – this may cause problems for a vaginal delivery
- unusual facial features, including deep-set eyes, a broad and flattened nose, small jaw and low-set ears
- deformities of the limbs due to fetal restriction and compression caused by lack of amniotic fluid
- general failure to thrive after birth.
Infants and children with ARPKD may have the following additional problems:
- polyuria (frequent passing of large quantities of dilute urine)
- polydipsia (excessive thirst)
- fluid balance problems
- prolonged fevers
ARPKD is a genetic condition. In almost all children with the condition, it is possible to identify a mutation in a gene called PKHD1, which codes for a protein called fibrocystin.
Approximately 50 per cent of cases of ARPKD are diagnosed during pregnancy (prenatally) during an ultrasound. As early as 13 weeks of pregnancy, the kidneys appear ‘bright’ on a scan and may be enlarged. At 20 weeks of pregnancy, oligohydramnios (low or absent amniotic fluid) may be present indicating poor kidney function.
Oligohydramnios coupled with the large kidneys results in lung underdevelopment. Therefore, babies struggling to breathe in the first few weeks of life may need to be attached to a ventilator so they can get enough oxygen. Selective kidney removal, called a nephrectomy, can allow room for the lungs to expand in an infant, particularly where there is restricted movement of the diaphragm due to enlarged kidneys.
Hypertension is a major problem for those with ARPKD surviving beyond infancy. This can be effectively controlled with modern medicines, such as beta blockers.
Serious deterioration in kidney function will require dialysis treatment. This purifies the blood removing waste products in the absence of functioning kidneys. Dialysis for tiny babies is very difficult and only possible in highly specialised centres. Eventually a kidney transplant may be required.
Diagnosis may take place during prenatal ultrasound scanning from 13 weeks into pregnancy.
The Organisation is a Registered Charity in England and Wales No. 1085662 and Scotland No. SC038279. It provides information and support to patients and families affected by polycystic kidney disease. The Organisation holds regular information days, and provides peer-to-peer support through a network of volunteers based at renal units around the UK.
Group details last updated September 2014.