About Niemann-Pick type C disease
Niemann-Pick type C disease (NP-C) is an inherited neurovisceral disease caused by mutations in one of two genes (NPC1 and NPC2). It is characterized by a unique defect in cellular lipid trafficking that leads to toxic accumulation of lysosomal lipids.1,2
NP-C is commonly misdiagnosed and often remains undetected due to its heterogeneous clinical presentation, lack of clinical awareness of the disease and the need for complex biochemical testing.3 As a result, the journey to diagnosis can be long and frustrating for patients and their families.4
Timing and presentation of NP-C symptoms vary widely amongst patients and include a range of systemic and neurological signs that are not specific to the disease. Typical, early symptoms of NP-C, presenting in early infancy, include prolonged cholestatic jaundice, hepatosplenomegaly, hypotonia and delay in motor milestones.2
Vertical supranuclear gaze palsy (VSGP) is the most common neurological sign of NP-C but is rarely detected in early infancy. Vertical saccadic eye movement impairment is affected first so voluntary saccades should be tested by asking the patient to voluntarily look up and down.2
In the late infantile and juvenile periods a number of other highly variable and progressive neurological symptoms can present, for example, progressive cerebellar signs, ataxia, dystonia, dysphagia, dysarthria, gelastic cataplexy, and seizures. These may be accompanied by learning difficulties and behavioral problems.2
Progressive cognitive decline and motor symptoms usually appear in adolescence or early adulthood and can be accompanied by psychiatric symptoms, such as early-onset psychosis, paranoid delusions, hallucinations or delusional ideation.2 All of these symptoms increase in both severity and impact on quality of life as NP-C progresses.
Rates of disease progression and life expectancy vary widely; however, the majority of patients die between 10 and 25 years of age.3 The early onset of neurological symptoms i.e. in early childhood leads to faster deterioration and earlier death than for those affected in adolescence or adulthood as shown in Figure 1.2 Progressive neurological manifestations in NP-C have a profound effect on quality of life of both patients and their carers/family. Early identification of NP-C and therefore early treatment with symptomatic and disease-specific therapies can dramatically improve quality of life for all those affected.2
- Wraith JE, Imrie J. Understanding Niemann-Pick disease type C and its potential treatment. UK Blackwell Publishing, 2007.
- Patterson MC, Hendriksz CJ, Walterfang M, et al, on behalf of the NP-C Guidelines Working Group. Recommendations for the diagnosis and management of Niemann–Pick disease type C: An update. Mol Genet Metab 2012. 106(3):330-344.
- Vanier MT. Niemann-Pick disease type C.Orphanet J Rare Dis 2010;5:16.
- Klünemann H, Wraith E, Wijburg F. Niemann-Pick Type C Disease – Report on Results from the Niemann-Pick Type C Patient and Healthcare Professional Survey Eur Neurol Rev 2011;6(1):12–15.