Long-term tolvaptan therapy in a case of very early-onset polycystic kidney disease.

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic kidney disorder. Pathogenic variants in PKD1 and PKD2 genes are the main causes of ADPKD. Biallelic inheritance of pathogenic variants leading to very early-onset manifestations have been described in the literature. A female fetus was prenatally diagnosed with oligohydramnios, bilateral kidney enlargement, and hyperechogenicity at 31 weeks gestational age. The mother was known to have ADPKD from the family history. However, unusually early and very rapid progressive disease after birth led to genetic testing which found two PKD1 variants inherited from both parents. The patient was suffering from refractory arterial hypertension, chronic kidney disease, and respiratory distress leading to off-label use of tolvaptan in the neonatal period. Although the data on tolvaptan use in neonatal polycystic kidney disease remains limited, a 6-year treatment in this patient was well tolerated and may have mitigated kidney growth and disease progression.