Joubert syndrome with hippocampal malrotation in a 4-month-old male: A case report

Joubert syndrome is a rare autosomal recessive ciliopathy characterized by a distinctive midbrain-hindbrain malformation, with the "molar tooth sign" as its characteristic neuroimaging hallmark, resulting from cerebellar vermian hypoplasia, thickening and horizontalization of the superior cerebellar peduncles, and a deepened interpeduncular fossa. We report a 4-month-old male infant presenting with developmental delay and progressive weight loss. Brain Magnetic Resonance Imaging revealed the characteristic molar tooth sign, vermian hypoplasia, and an associated hippocampal malrotation, a less frequently recognized but increasingly documented supratentorial finding in Joubert syndrome and related disorders. The patient also had retinal degeneration and elevated transaminases, findings that raise concern for multisystem involvement within the Joubert ciliopathy spectrum. Hippocampal malrotation has been described as an associated supratentorial finding in JS, but its clinical significance, including any relationship with epilepsy, remains uncertain. This case emphasizes careful evaluation of both infratentorial and supratentorial structures and systemic assessment in patients with JS.