Niemann-Pick disease type C is an autosomal recessive disorder with a prevalence of 1:120,000 in Northern Europe and an unknown prevalence in the Chinese. 95% of patients have a disorder of cholesterol metabolism due to mutations in the lysosomal membrane protein NPC1 gene, and the other 5% are due to mutations in the lysosomal soluble protein NPC2 gene. The clinical manifestations due to the two mutations are not significantly different. According to the age of onset, Niemann-Pick disease type C can be divided into perinatal, early infantile, late infantile, adolescent, and adult types. The perinatal period is defined as the period from birth to 3 months of age and may present with fetal edema, prolonged jaundice, pulmonary infiltration, hepatosplenomegaly, dystonia, and psychomotor retardation. Prolonged jaundice is of particular concern, and any patient diagnosed with infantile hepatitis syndrome requires further testing to rule out Niemann-Pick disease type C. The early infantile form, which develops after the first 3 months of life and up to the age of 2 years, is characterized by a delayed motor development and hypotonia, and an enlarged spleen on physical examination. The late infantile form, which develops between the ages of 2 and 6 years, presents with vertical supranuclear gaze palsy and early downward gaze palsy, which is not easily recognized; patients are usually seen for ataxia, which presents with unsteady walking, falls, dystonia, insidious progressive cognitive impairment, some progression to seizures, and an enlarged spleen on physical examination. About 50% of patients have a clinical manifestation specific to the disease, sudden collapse with demented laughter, which is a sudden decrease in muscle tone after laughing and sitting paralyzed on the floor. The adolescent form is the onset of the disease between the ages of 6 and 15. Patients present with learning difficulties, unsteady walking gait, easy falling, most have seizures, and an enlarged spleen is found on physical examination. The adult form has a onset at the age of 15 years or older, with psychiatric symptoms as the first manifestation, such as delusions, mania, and obsessive-compulsive disorder, which can be easily misdiagnosed as psychosis, and the patient gradually shows dystonia, ataxia, and mental retardation. Not all adult patients have an enlarged spleen.