A young adult patient presents with bilateral renal cysts; what genetic condition is likely responsible?

The presence of bilateral renal cysts in a young adult is highly suggestive of autosomal dominant polycystic kidney disease (ADPKD). This genetic condition is characterized by the development of multiple cysts in the kidneys, which can lead to progressive renal dysfunction over time. ADPKD typically manifests in adulthood, hence the patient's age aligns with the expected presentation of this condition. It is caused by mutations in either the PKD1 or PKD2 genes, with PKD1 mutations generally leading to a more severe phenotype.

ADPKD can also have extra-renal manifestations such as liver cysts, pancreatic cysts, and hypertension, further supporting the diagnosis. The bilateral nature of the cysts is a distinctive feature, as unilateral cysts are less common and suggest alternative pathologies.

Other conditions associated with renal cysts, such as autosomal recessive polycystic kidney disease, usually manifest in childhood and are characterized by different clinical features. Medullary sponge kidney and nephronophthisis do not typically present with bilateral cysts in the same way that ADPKD does and have distinct patterns of inheritance and clinical findings. Thus, the clinical presentation and genetic basis strongly point toward autosomal dominant polycystic kidney