Autosomal recessive polycystic kidney disease

December 31, 2014

Synonyms

Overview

Autosomal recessive polycystic kidney disease is a genetic condition that is characterized by the growth of cysts in the kidneys (which lead to kidney failure) and liver and problems in other organs, such as the blood vessels in the brain and heart. The severity varies from person to person. It is the recessive form of polycystic kidney disease. and it is associated with a group of congenital fibrocystic syndromes.

Symptoms

The signs of ARPKD frequently begin before birth, so it is often called "infantile PKD" but some people do not develop symptoms until later in childhood or even adulthood. Children born with ARPKD often, but not always, develop kidney failure before reaching adulthood; babies with the worst cases die hours or days after birth due to respiratory difficulties or respiratory failure. Liver scarring occurs in all patients.

Causes

Autosomal recessive polycystic kidney disease (ARPKD) is inherited in an autosomal recessive manner. This means that an affected individual has two gene alterations (mutations) in the PKHD1 gene, with one mutation inherited from each parent. Each parent, who has one altered copy of the gene, is referred to as a carrier. Carriers do not typically show signs and symptoms of the condition. When two carriers for an autosomal recessive condition have children, each child has a 25% (1 in 4) risk to have the condition, a 50% (1 in 2) risk to be an unaffected carrier like each of the parents, and a 25% chance to not have the condition and not be a carrier. This means that with each pregnancy, there is a 75% (3 in 4) chance to have an unaffected child.

Diagnosis

Ultrasonography is the primary method to evaluate autosomal recessive polycystic kidney disease (ARPKD),particularly in the perinatal and neonatal. Diagnostic criteria require two or more cysts in one kidney and at least one cyst in the contralateral kidney in young subjects, but four or more in subjects older than 60 years, because of the increased frequency of benign simple cysts. Most often, the diagnosis is made from a positive family history and imaging studies showing large kidneys with multiple bilateral cysts and possibly liver cysts. Before the age of 30 years, CT scan or T2-weighted MRI is more sensitive for detecting presymptomatic disease because the sensitivity of ultrasound falls to 95% for ADPKD type 1 and <70% for ADPKD type 2. Genetic counseling is essential for those being screened. It is recommended that screening for asymptomatic intracranial aneurysms should be restricted to patients with a personal or family history of intracranial hemorrhage. Intervention should be limited to aneurysms larger than 10 mm. Someone with this disease has a 5% chance of getting brain aneurysms. Von Meyenburg complex is often co-existent with autosomal recessive polycystic kidney disease.

Treatment

The treatment options for autosomal recessive polycystic kidney disease, given there is no current cure, are:

medications to deal with hypertension
medications and/or surgery for pain
antibiotics in the event of any infection
kidney transplantation, in more serious cases
and dialysis should there be renal failure

Although a cure or treatment for the underlying genetic cause of autosomal recessive polycystic kidney disease does not exist, advancements have been made in showing improvement of liver and kidney disease in mouse models of the condition by disrupting the function of certain cell receptors.

Medical management is currently symptomatic and involves supportive care. Mechanical ventilation may be used to treat the underdevelopment of the lungs and breathing issues caused by the kidneys that are enlarged due to the numerous cysts. When the kidneys are severely enlarged, one or both kidneys may be removed (nephrectomy). Dialysis may be required during the first days of life if the infant is producing little urine (oliguria) or no urine (anuria). Low levels of sodium (hyponatremia) may occur and is treated with diuresis and/or sodium supplementation depending on the individual's specific levels. High blood pressure (hypertension) is treated with medication. Kidney failure requires dialysis, and kidney transplantation is another option. Poor eating and growth failure may be managed with gastrostomy tubes. Growth hormone therapy may be used to treat the growth failure and kidney insufficiency. Urinary tract infections are treated with antibiotics. Those with liver involvement may require shunt to treat the progressive high blood pressure and possibly liver transplantation.