Medullary Nephrocalcinosis as the Initial Manifestation of Joubert Syndrome with a Novel INPP5E Mutation: A Case Report

Joubert syndrome (JS) is a rare, autosomal recessive ciliopathy characterized by neurological abnormalities and, less commonly, renal, retinal, and hepatic involvement. We report a 13-year-old male with developmental delay and abdominal pain. He was diagnosed with bilateral medullary nephrocalcinosis. Detailed examination revealed truncal ataxia and bilateral retinitis pigmentosa. MRI of the brain showed the characteristic molar tooth sign, and genetic testing identified a novel homozygous c.1304G>A (p.Arg435Gln) variant in exon 6 of the INPP5E gene. This report expands the known phenotypic spectrum of INPP5E -related JS and emphasizes the importance of recognizing syndromic associations in patients with unusual renal findings.