Niemann–Pick disease type C

A rare genetic disorder affecting lipid metabolism

Niemann–Pick disease type C (NPC) is a rare, inherited, neurodegenerative disorder that affects the body's ability to metabolize cholesterol and other lipids within cells. These lipids accumulate in the liver, spleen, and brain, leading to a variety of symptoms. NPC is one of a group of diseases known as lysosomal storage disorders.

Pathophysiology

Structure of the NPC1 protein, which is involved in cholesterol transport.

Niemann–Pick disease type C is caused by mutations in either the NPC1 or NPC2 genes. These genes are responsible for producing proteins that are essential for the transport of cholesterol and other lipids within cells. The NPC1 protein is a large membrane protein located in the lysosome, while the NPC2 protein is a small soluble protein that binds cholesterol. Mutations in these genes disrupt normal lipid transport, leading to the accumulation of cholesterol and other lipids in the lysosomes.

Clinical Presentation

The symptoms of NPC can vary widely among affected individuals and can appear at any age from infancy to adulthood. Common symptoms include:

• Hepatosplenomegaly (enlarged liver and spleen)
• Ataxia (lack of muscle coordination)
• Dysarthria (difficulty speaking)
• Dysphagia (difficulty swallowing)
• Dementia
• Seizures
• Vertical supranuclear gaze palsy (difficulty moving the eyes up and down)

Diagnosis

Diagnosis of NPC is challenging due to the variability of symptoms. It often involves a combination of clinical evaluation, family history, and specialized tests. These tests may include:

• Filipin test: A biochemical test that detects cholesterol accumulation in skin fibroblasts.
• Genetic testing: Identifies mutations in the NPC1 or NPC2 genes.
• Liver biopsy: May show characteristic storage material.

Treatment

Currently, there is no cure for NPC, but treatments are available to manage symptoms and improve quality of life. These include:

• Miglustat: An oral medication that may slow neurological progression.
• Supportive therapies: Physical therapy, occupational therapy, and speech therapy.
• Palliative care: To manage symptoms and provide comfort.

Prognosis

The prognosis for individuals with NPC varies depending on the age of onset and severity of symptoms. Early-onset forms tend to be more severe and progress more rapidly, while later-onset forms may have a slower progression.

Research

Research into NPC is ongoing, with studies focusing on understanding the disease mechanisms and developing new treatments. Gene therapy and other novel approaches are being explored as potential future therapies.

Related pages

• Lysosomal storage disorder
• Cholesterol metabolism
• Genetic disorder

File:Novascotiayarmouthcountydet.gif

Map of Yarmouth County, Nova Scotia, where a cluster of NPC cases has been studied.