Arimoclomol Prospective Study in Participants Diagnosed With Niemann-Pick Disease Type C

Inclusion Criteria: EITHER NP-C participants who have entered the CT-ORZY-NPC-001 study and who have completed Visit 2 (EOS) of the CT-ORZY-NPC-001 study. OR NPC participants who did not enter or complete the CT-ORZY-NPC-001 study but are fulfilling all of criteria listed below: ◦Diagnosis of NPC1 or NPC2; NPC diagnosis confirmed by: * Genetically confirmed (deoxyribonucleic acid \[DNA\] sequence analysis) by mutations in both alleles of NPC1 or NPC2, OR * Mutation in only one allele of NPC1 or NPC2 plus either positive filipin staining or elevated cholestane triol/oxysterols (\>2 x upper limit of normal). * Males and females aged from 2 years to 18 years and 11 months; * Treated or not treated with miglustat; * If a participant is under prescribed treatment with miglustat, it has to be under stable dose of the medication for at least 6 continuous months prior to inclusion in the CT-ORZY-NPC-002 study; o If a participant has been discontinued from prescribed treatment with miglustat, they must have been discontinued for at least 3 continuous months prior to inclusion in the CT-ORZY-NPC-002 study; * Body mass index (BMI) Z score ≥ -2 SD (standard deviation) for age, according to the World Health Organisation (WHO) standards; * Presenting at least one neurological symptom of the disease (for example, but not limited to, hearing loss, vertical supranuclear gaze palsy, ataxia, dementia, dystonia, seizures, dysarthria, or dysphagia); * Ability to walk eithe…