Autosomal recessive polycystic kidney disease

Autosomal recessive polycystic kidney disease or ARPKD is a rare pathology with an incidence of 1 case per 20,000 live births that is of special importance in pediatric nephrology.

ARPKD is caused by pathogenic variants in the PKHD1 gene that codes for a protein called fibrocystin which is mostly expressed in the organs affected by the disease (liver, kidneys and pancreas). Fibrocystin plays a key role in the development of the renal tubules and bile ducts.

ARPKD manifests during gestation or in the first months of life, rarely in adolescence. The earlier the onset, the greater the severity of symptoms. The disease is characterized by variable dilatation of the collecting tubules of the kidneys and the bile ducts of the liver.

The kidneys are enlarged and present numerous microcysts corresponding to collecting tubules dilated by fluid accumulated inside them. The cysts exert a compressive effect on healthy tissue, leading to progressive destruction of the nephrons, which are the basic structural units of the kidney involved in blood filtration. On the other hand, extra-renal symptoms such as hypertension, anemia, liver fibrosis and pulmonary hypoplasia may occur. Approximately half of the people with polycystic kidney disease have cysts in the liver.

The goal of the available treatments is to control symptoms and prevent complications. If the disease is detected before birth, amniotic fluid replacement may be applied. After birth, assisted ventilation, dialysis and treatment of hypertension are used. Chronic renal failure is treated conservatively, preventing as much as possible renal osteodystrophy (complications of bone and mineral metabolism associated with chronic renal disease).

The definitive treatment is renal transplantation, but the degree of existing liver damage must be assessed, which is sometimes so severe that it requires liver transplantation. Survival depends on the severity of symptoms in the neonatal period.