Polycystic kidney disease and inherited nephropathies: Case

This neonate has the perinatal form of autosomal recessive polycystic kidney disease, confirmed by the homozygous PKHD1 mutation. The PKHD1 gene encodes fibrocystin, a protein found on the primary cilium of collecting duct and biliary epithelial cells, and its defect explains the simultaneous involvement of the kidneys and the biliary tract. The bilateral enlarged echogenic kidneys with oligohydramnios, the respiratory distress from pulmonary hypoplasia, and the severe hypertension are the classical presenting features. His thrombocytopenia, splenomegaly and portal hypertension on Doppler confirm congenital hepatic fibrosis, which is a defining feature of ARPKD that demands the same clinical attention as the kidney disease. ^[2]

Clinical findings

The clinical picture is one of multisystem disease from a single gene defect. The massively enlarged kidneys are palpable as bilateral flank masses and are distending his abdomen. The pulmonary hypoplasia from the oligohydramnios sequence has necessitated mechanical ventilation from birth, and the restricted lung capacity is compounded by the enlarged kidneys splinting the diaphragm. His blood pressure of 98 over 65 in a term neonate is significantly elevated, and severe hypertension is one of the most dangerous early complications of ARPKD because it can cause cardiac failure, intracranial haemorrhage and accelerated kidney damage. ^[1]

The hepatic involvement is already clinically apparent. The thrombocytopenia of 75 times 10 to the 9 per litre with palpable splenomegaly indicates hypersplenism from portal hypertension, and the Doppler findings confirm the congenital hepatic fibrosis that accompanies ARPKD because the fibrocystin defect affects the biliary epithelium. This is the dual challenge of ARPKD: the kidney disease causes hypertension, electrolyte disturbance and progressive renal failure, while the hepatic fibrosis causes portal hypertension that may result in life-threatening variceal bleeding. Management must address both simultaneously, with nephrology and hepatology working as one team. ^[1]