Niemann-Pick disease type C, juvenile neurologic onset

Niemann-Pick disease type C (NPC) with juvenile neurologic onset is a rare lysosomal storage disorder characterized by impaired intracellular lipid trafficking, leading to the accumulation of unesterified cholesterol and glycosphingolipids in various tissues, particularly the brain, liver, and spleen. NPC is caused by mutations in the NPC1 gene (approximately 95% of cases) or the NPC2 gene (approximately 5% of cases). The juvenile neurologic onset form typically presents between 6 and 15 years of age and is one of several clinical subtypes of NPC, which also include perinatal, early infantile, late infantile, and adult-onset forms. The juvenile onset form is among the most common presentations of NPC. Key neurological features include progressive cerebellar ataxia (difficulty with coordination and balance), vertical supranuclear gaze palsy (VSGP, an inability to voluntarily move the eyes vertically), dysarthria (slurred speech), dysphagia (difficulty swallowing), cognitive decline, and gelastic cataplexy (sudden episodes of muscle weakness triggered by laughter or strong emotions). Psychiatric symptoms such as behavioral problems and learning difficulties may also be prominent. Hepatosplenomegaly (enlargement of the liver and spleen) may be present but can be mild or absent in this age group. The disease follows a progressive course, with neurological deterioration leading to significant disability over years to decades. The only disease-specific approved therapy is miglustat (Zavesca), which has been approved in the European Union and several other countries for the treatment of progressive neurological manifestations of NPC. Miglustat acts as a substrate reduction therapy by inhibiting glucosylceramide synthase, and clinical studies have shown it can stabilize or slow the progression of neurological symptoms. Supportive and symptomatic management remains essential and includes physical therapy, speech therapy, management of seizures, and nutritional support. Intrathecal 2-hydroxypropyl-β-cyclodextrin (arimoclomol and other investigational agents) has been explored in clinical trials, though results have been mixed. Early diagnosis and initiation of treatment are important for optimizing outcomes.

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