Niemann-Pick disease type C
What is Niemann-Pick Disease Type C?
Niemann-Pick disease type C is an inherited condition in which the body cannot properly metabolize cholesterol and fats, resulting in an excess of these substances in the body. Cholesterol buildup in the liver causes severe liver disease, and fat accumulation in the brain leads to learning disabilities and progressive neurological symptoms.
The first symptom of the disease, which can appear at any age from infants to adults, is an enlarged liver, enlarged spleen, or jaundice. In some cases, it is possible to detect the disease in an unborn child via ultrasound, but the disease is most commonly diagnosed in school-aged children. Symptoms may include sudden muscle problems such as seizures, clumsiness, tremors, problems walking, sudden falls, slurred speech, and trouble moving the eyes up and down. As the condition progresses, these children develop learning disabilities, psychological problems, or even dementia, and often lose the ability to speak. Eventually, people with Niemann-Pick disease type C lose the ability to move their facial muscles or swallow, making feeding through a stomach tube necessary.
For those diagnosed during childhood, the disease is usually fatal in the late teens or twenties due to pneumonia. People diagnosed in adulthood generally survive 10 to 20 years after diagnosis.
At the cellular level, Niemann-Pick disease type C can be caused by two different genetic mutations. Type C1 is caused by a mutation in the NPC1 gene, and type C2 is caused by a mutation in the NPC2 gene. Although the genetic mutations are different, the resulting symptoms are the same because NPC1 and NPC2 must work together to remove cholesterol and lipids from body cells. Of the known cases of Niemann-Pick disease type C, 95% have been type C1 while 5% have been C2.
How common is Niemann-Pick Disease Type C?
Niemann-Pick disease type C is estimated to affect 1 in 150,000 people. It is more common among French Acadians in Nova Scotia, people of Hispanic descent in specific parts of Colorado and New Mexico, and a small Bedouin group in Israel.
How is Niemann-Pick Disease Type C treated?
At this time, there is no cure for Niemann-Pick disease type C. Treatment focuses on managing symptoms with medication for seizures, sedatives for sleep disturbances, physical therapy to maintain mobility, and speech therapy to preserve communication as long as possible. Chest physiotherapy and antibiotics may help to prevent regular lung infections. People with the condition need a gastronomy tube for feeding when they can no longer swallow well enough to avoid choking or malnutrition.
What is the prognosis for a person with Niemann-Pick Disease Type C?
Niemann-Pick disease type C is usually fatal 10 to 20 years after diagnosis. In children who show symptoms at an early age, disease progression is usually faster compared to people whose symptoms appear later in life. Over half of people with this disease will be diagnosed by the age of 10.