ARPKD

Autosomal recessive polycystic kidney disease (ARPKD) is a rare genetic disorder characterized by dilation of the collecting ducts in the kidneys and fibrosis of the liver, especially the portal areas. The condition typically presents in infancy, though milder cases may appear in childhood. Kidney changes produce enlarged, echogenic kidneys with many small cysts; hepatic involvement is congenital hepatic fibrosis that can progress to portal hypertension. ARPKD results from biallelic mutations in PKHD1, on chromosome 6, which encodes fibrocystin, a protein involved in duct structure and function in kidney and biliary tract.

Genetics and inheritance: ARPKD follows an autosomal recessive pattern. A child must inherit two defective PKHD1 copies, one from each parent, who are typically asymptomatic carriers. The condition shows substantial clinical variability, ranging from severe neonatal disease to milder forms presenting later in childhood. Large-scale population screening is not routine.

Clinical features and diagnosis: In utero, ARPKD may cause enlarged, hyperechoic kidneys and reduced amniotic fluid. After birth, infants may have poor urine output, hypertension, and progressive renal dysfunction. Hepatic involvement often appears later as congenital hepatic fibrosis, contributing to portal hypertension. Ultrasound is a key diagnostic tool, showing enlarged kidneys with multiple small cysts; genetic testing for PKHD1 mutations confirms the diagnosis and distinguishes ARPKD from other cystic kidney diseases.

Management and prognosis: There is no cure; care is supportive and multidisciplinary. Blood pressure control and preservation of kidney function are central. Some patients require renal replacement therapy in infancy or childhood, including dialysis or kidney transplantation. Severe liver disease can complicate management; rare cases may require combined liver-kidney transplantation. With advances in care, survival has improved, but prognosis depends on the severity of kidney and liver involvement.