ALSP is a disease caused by a rare mutation in the CSF1R gene on chromosome 5. It is an autosomal dominant disease, meaning that each child born to someone who has the CSF1R gene mutation has a 50% chance of also having this mutation. Because ALSP is often diagnosed after the childbearing years, most individuals have already had children by the time they are aware they have the disease. Currently there is no newborn genetic testing for the CSF1R gene mutation that causes ALSP.
The CSF1R mutation affects cells within the body that are part of the immune system. These cells are called macrophages and microglia. The mutation causes neurons to be misshapen due to the presence of spheroids in part of the cell. Macrophages take myelin away from the misshaped neurons which causes further damage. The CSF1R mutation also leads to underactive microglia, cells that are normally protective for neurons. The combination of neuron spheroids, lack of myelin, and underactive microglia are what cause the symptoms of ALSP.
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