This disease is characterized by the body’s inability to metabolize the fats within the cells. As the result, these cells can malfunction and die over time. It can affect multiple systems of the body such as the brain, liver, spleen, bone marrow and the lungs. Niemann-Pick disease can occur at any age but mainly affects the children. There are four main types of this disease; type A, type B, type C1 and type C2. These different types are classified based on the genetic cause and the symptoms evident.
Causes
Type A and type B develops because of the mutations in the gene SMPD1 which produces an enzyme called acid sphingomyelinase that is found in the lysosomes of the cells. The lysosomes are responsible for the breaking down and recycling different types of molecules. This enzyme is responsible for the transformation of lipid called sphingomyelin into another lipid called ceremide and the genetic mutation results in the shortage of this enzyme. Hence, the fat can accumulate in the cells causing them to malfunction and die. Genetic mutations in the gene NPC1 or NPC2 causes the type C which is necessary for the movement of lipids in the cells. The shortage of the functional protein results in preventing the cholesterol movement causing them to accumulate in cells.
Symptoms
The symptoms of this condition are based on the types of the disease. The symptoms of type A may be apparent within the first few months of the child’s life, the type B may not occur for years and type C may not develop until adulthood. The symptoms of this disease can include clumsiness and difficulty walking, recurrent pneumonia, difficulty swallowing and eating, sleep disturbances and excessive muscle contractions or eye movements.
Diagnosis
The diagnosis is based on a physical examination, symptoms evident, medical history and family history of the affected individual. The type A and B can be diagnosed based on the blood or the skin sample that measure the amount of sphingomyelinase in the white blood cells. The diagnosis of type C is based on the skin sample that is assessed to determine how the cells move and store cholesterol. Additional tests can include MRI to detect the loss of brain cells and an eye examination to identify signs of the disease. A genetic testing can also help confirm the diagnosis by detecting the genetic mutation responsible for the cause of the disease.
Treatment
There is no cure for the disease and no effective treatment available for the type A and B. Research still continues to find the possible treatment options including enzyme replacement and gene therapy. In the case of high cholesterol, this can be managed with a low-cholesterol diet or with medications. Additional treatment options include medications to provide relief from the symptoms such as the seizures and loss of muscle tone.
References
https://medlineplus.gov/ency/article/001207.htm
https://ghr.nlm.nih.gov/condition/niemann-pick-disease#genes
