Niemann-Pick Disease Type C (NPC) is a rare, genetic neurodegenerative disease that currently has no cure. However, as the science of this disease becomes better understood, new and promising treatments are being developed. Read below to find out more about the nature of the disease, the signs that a child may have NPC, and treatment options for those who have been diagnosed.
NPC is a rare genetic neurodegenerative disease that is estimated to affect only 1 in 150,000 people. NPC belongs to a larger group of more than 50 disorders known as lysosomal storage disorders. Patients with NPC disease are unable to make functional NPC protein, which is used by cells in the body to recycle cholesterol and lipids through the lysosome to other parts of the cell. The absence of functional NPC protein causes a toxic accumulation of cholesterol and other lipids in the lysosomes, while other parts of the cell are starved. This results in cell death and leads to irreversible organ damage, including brain damage.
NPC is a progressive disease, meaning symptoms typically appear in early childhood and worsen over time. As the disease progresses, many symptoms become life threatening and most children do not live to adulthood. While treatments are being developed that may help slow the disease progression, there is currently no cure for NPC.
All human cells have 23 pairs of chromosomes that carry each person’s unique, genetic information. NPC disease is caused by mutations in the NPC gene, which is found on chromosome 18. The NPC gene provides the instructional code for the cell to make the NPC protein, which is needed to transport cholesterol and other lipids out of the lysosome for their reuse by the cell. If the NPC gene is mutated, the NPC protein may not be made properly, so that it cannot do its job, or it may not be made at all.
All human cells have two copies of each gene, one copy passed down from the mother and one from the father. NPC is an autosomal, recessive genetic disease, which means that both copies of the gene must be mutated for disease to occur. NPC is inherited when both parents are carriers of an NPC mutation, meaning each parent has one mutated copy of the gene and one normal copy of the gene. Carriers do not have any symptoms and often don’t know they carry a mutation, because they have one normal gene copy that codes for functional NPC protein. When both parents are carriers of a mutated NPC gene, each pregnancy has a 25 percent chance of producing a baby with NPC.
NPC is a progressive disease with a strong neurodegenerative component, although patients can experience issues with other organs including the liver, spleen and lung. Many patients exhibit symptoms beginning at infancy or in early childhood. However, because of the diverse nature of the symptoms and the rarity of the disease, diagnosis can often take years.
Early onset symptoms can include:
- Enlargement of the liver and spleen. Sometimes this is the first symptom and should not be taken lightly. Patients may experience a reduction in appetite, stomach distension and/or pain. Blood platelets may also be low as a result.
- Lack of muscle coordination. This results in difficulty with balance and walking, and can manifest as having an unsteady gait, clumsiness, and frequent falling.
- Hand tremors or difficulty with fine motor skill development. Teachers often report a child’s difficulty in drawing or writing.
- Vertical supranuclear gaze palsy. This means the patient loses the ability to move his or her eyes up or down.
- Slurred or unintelligible speech. Children with the disease may regress after speech skills have been learned.
Progressive conditions of the disease include:
- Progressive decline in all motor skills, until the patient is unable to move independently.
- Difficulty swallowing. Patients may eventually require a feeding tube to receive adequate nutrition.
- Cognitive impairment. A progressive deterioration of intellectual ability and loss of memory can occur.
- Hearing loss. Partial hearing loss is possible with NPC cases.
- Epileptic seizures. Some patients may have seizures as the disease progresses.
Firefly Fund was created because there is currently no cure for NPC. Current therapies focus on treatment of symptoms including seizure medication, sedatives for sleep issues, physical therapy to attempt to reduce mobility issues and speech therapy to help with communication as much as possible.
However, rare disease drug development company Vtesse is currently engaged in phase 3 clinical trials that seek FDA approval for a promising new drug called VTS-270. VTS-270, a form of hydroxypropyl-beta-cyclodextrin, has been shown in mouse and cat models of NPC to reduce accumulation of cholesterol in lysosomes, reduce cell death and brain damage, and lengthen lifespan.