Bilineal inheritance of PKD1 abnormalities mimicking autosomal recessive polycystic disease

Dominant polycystic kidney disease is common and usually presents clinically in adulthood. Recessive polycystic kidney disease is much less common and frequently presents antenatally or in the neonatal period with severe renal involvement. These are usually thought of as clinically distinct entities but diagnostic confusion is not infrequent. We describe an infant with antenatally diagnosed massive renal enlargement and oligohydramnios with no resolvable cysts on ultrasound scanning. He underwent bilateral nephrectomy because of respiratory compromise and poor renal function but died subsequently of overwhelming sepsis. Genetic analysis revealed that he had bilineal inheritance of abnormalities of PKD1 and no demonstrable abnormalities of PKD2 or PKHD1. Biallelic inheritance of abnormalities of PKD1 may cause extremely severe disease resembling autosomal dominant polycystic kidney disease (ADPKD) which can result in diagnostic confusion. Accurate diagnosis is essential for genetic counseling.