Niemann-Pick type C disease (NP-C) is a treatable disease.
It affects all ages.
Could it be NP-C?
What is NP-C?
NP-C is a progressive, irreversible and chronically debilitating lysosomal storage disease. It is caused by a defect in lipid transportation within the cell. This leads to intracellular accumulation of lipids in the brain, liver and spleen causing the symptoms of NP-C.1-3
NP-C is an inherited condition and can present at any age, affecting infants, children, adolescents and adults. The incidence of NP-C is approximately 1 in 120,000 live births.1-3 However, this is likely to be an underestimate due to a lack of clinical awareness of the disease and the difficulty in recognising NP-C because of its highly heterogeneous clinical presentation.1
NP-C is commonly undetected or misdiagnosed. This is often due to its highly variable clinical presentation characterised by a wide range of symptoms that, individually, are not specific to the disease.1,3 The journey to diagnosis can therefore be long and frustrating for patients and their families. The average delay in diagnosis is five to six years from onset of neurological symptoms.4
Why is early diagnosis of NP-C critical for patients?
Early diagnosis means patients can access support, which can improve their quality of life and the lives of those around them.1 Early diagnosis is also important as NP-C is a treatable disease. Treatment can help to manage the symptoms and can slow down the progression of the disease.1,3
What are the symptoms of NP-C?
Key symptoms of NP-C – click for full sizeEarlier recognition of key symptoms of NP-C is critical in order to achieve an earlier diagnosis for patients. The symptoms of NP-C can be categorised as systemic (visceral), neurological or psychiatric.1 The most common symptoms are shown in the table on the right.1,2
One of the strongest indicators of NP-C is when a patient presents with symptoms in more than one of these categories. Therefore, linking these symptoms together can facilitate fast and differential diagnosis of NP-C.3
Age of onset –click for full size Symptoms present at different ages and in different combinations.1 The age of onset of visceral symptoms is independent of the onset of neurological disease, which occurs along a continuous spectrum with considerable overlap between the age categories as shown in the diagram (Vanier 2010).2
How is NP-C diagnosed?
NP-C can be difficult to recognise because the symptoms can occur at different times and with varying severity in each person.1 For some patients, symptoms are quickly linked to NP-C if their doctor knows about NP-C. However, for others, it may take many different doctors a number of years to finally link them together and suspect NP-C as there is a lack of clinical awareness about the disease.2 Once NP-C is suspected patients are referred on to a specialist centre for diagnostic testing.3
If you suspect a patient has NP-C then you can find details of specialist centres in your country on Suspect NP-C?
Where can I find out more about NP-C?
www.NPC-info.com is an Actelion-sponsored website containing comprehensive information about the symptoms, diagnosis and management of NP-C.
www.Orpha.net is a database of information on rare diseases and orphan drugs that aims to help improve the diagnosis, care and treatment of patients with rare disease.
www.INPDA.org is the International Niemann-Pick Disease Alliance (INPDA) website that provides information about the non-profit organisations that are in place across the globe to support patients and families diagnosed with NP-C.
www.INPDR.org is the International Niemann-Pick Disease Registry (INPDR) website, which provides information about all types of Niemann-Pick diseases and the importance of the registry in collecting data.
You can also find more information on the INPDA member organisation websites, which can be found on About the INPDA.
How to check for NP-C
The following tools and resources aim to support healthcare professionals to understand more about NP-C, the key symptoms of NP-C and how to check for eye movement abnormalities so suspected patients can be referred on to a specialist centre for diagnostic testing.
How to check for eye movement abnormalities
VIDEO: how to test for VSGPVertical supranuclear gaze palsy (VSGP) is a typical symptom of NP-C and is present in virtually all patients with NP-C. It often goes undetected, despite it being simple to detect by testing for impairment of voluntary saccades, which is an early sign of NP-C.1,2 All healthcare professional specialties that might see a patient with NP-C and see one or more of the symptoms listed in the Key symptoms of NP-C table should check for eye movement abnormalities.
Two step process to test for VSGP:
How to check for VSGP – click for full sizeTo assess the smooth pursuit, patients should be tested for their ability to follow an object
To assess the vertical saccades the physicians will ask the patient to spontaneously move their gaze up and down without following an object (ask to look between two points fixed by the upper part of their head and at chest level)
Educational slide set for healthcare professionals
Download the slide setThis slide set aims to support healthcare professionals to recognise the signs and symptoms of NP-C. Feel free to download this slide set for your own information and to present to other healthcare professionals at appropriate meetings or conferences.
Tools to aid suspicion of NP-C
The following tools can support healthcare professionals to suspect NP-C by linking key presenting symptoms together.
NP-C Suspicion Index – www.NPC-SI.com
A simple screening tool that has been developed by Actelion Pharmaceuticals Ltd in collaboration with a group of international experts in the field of NP-C. It aims to enhance the detection of NP-C among patients suspected of having the condition in order to establish an earlier diagnosis.1,3
FindZebra – http://www.findzebra.com/
A specialised search engine supporting healthcare professionals to understand possible diagnoses for difficult patient cases by typing in the symptoms that a patient presents with
Patterson M, Hendriksz, 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):330-44.
Vanier, M. Niemann-Pick disease type C. Orphanet J Rare Dis 2010; 5:16.
Wijburg F, Sedel F, Pineda M, et al. Development of a suspicion index to aid diagnosis of Niemann-Pick disease type C. Neurology 2012;78(20):1560-7.
Mengel E, Klünemann H, Louren?o C, et al. Niemann-Pick disease type C symptomatology: an expert-based clinical description. Orphanet J Rare Dis 2013; 8:166.