Mania in Juvenile Neuronal Ceroid Lipofuscinosis (CLN3 Disease): A Rare Neuropsychiatric Presentation in an Adolescent.

Juvenile neuronal ceroid lipofuscinosis (JNCL; CLN3 disease) is a rare autosomal recessive neurodegenerative lysosomal storage disorder characterized by childhood-onset progressive visual loss, epilepsy, and cognitive decline. Although behavioral and emotional symptoms are frequently reported, manic episodes remain rarely characterized within a structured diagnostic framework. We present a 16-year-old girl with progressive visual impairment and epilepsy who developed a manic episode with psychotic features meeting Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria, including decreased need for sleep, increased goal-directed activity, hypersexuality, pressured speech, and hallucinations. Genetic testing using whole exome sequencing identified a homozygous likely pathogenic variant in CLN3 (c.898C>T), which was also identified in her affected sibling, further supporting the diagnosis of JNCL. The patient showed significant clinical improvement with antipsychotic treatment and multidisciplinary follow-up. This report delineates the neuropsychiatric spectrum associated with CLN3 disease and supports the need for systematic mood symptom monitoring in affected adolescents. These findings should be interpreted as hypothesis-generating, and further studies are needed to clarify the underlying mechanisms.