What is Niemann-Pick Disease Type C2?
Niemann-Pick disease type C is an inherited lysosomal-storage disorder. Niemann-Pick disease type C is caused by harmful changes, or mutations, in two different genes, NPC1 and NPC2. Individuals with Niemann-Pick disease type C cannot properly break down cholesterol and fats. In individuals with Niemann-Pick disease type C, cholesterol buildup causes severe liver disease, and fat accumulation in the brain which leads to learning disabilities and progressive neurological symptoms.
Niemann-Pick disease type C1 is caused by mutations in the NPC1 gene, and type C2 is caused by mutations in the NPC2 gene. Although the mutations occur in different genes, the resulting symptoms are the same, because NPC1 and NPC2 work together to remove cholesterol and lipids from cells. Approximately 90% of known cases of Niemann-Pick disease type C have been type C1 and 4% have been type 2.
The first symptoms of the disease, which can appear at any age from infancy to adulthood, 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, affected children develop learning disabilities, psychological problems, dementia, and often lose the ability to speak. Eventually, individuals with Niemann-Pick disease type C lose the ability to move their facial muscles or swallow, making feeding through a stomach tube necessary.
How common is Niemann-Pick Disease Type C2?
The exact incidence of Niemann-Pick Disease Type C2 is unknown. It is estimated that Niemann-Pick disease type C affects 1 in 150,000 individuals, with approximately 4% of these cases attributed to mutations in the NPC2 gene.
How is Niemann-Pick Disease Type C2 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. Individuals 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 an individual with Niemann-Pick Disease Type C2?
Niemann-Pick disease type C shows variable disease advancement, with an earlier onset associated with faster disease progression. For those diagnosed during childhood, the disease is usually fatal in the late teens or twenties, due to pneumonia. Over half of those with this disease will be diagnosed by the age of 10. Individuals diagnosed in adulthood generally survive 10 to 20 years after diagnosis.