ALSP Genetics

ALSP is caused by a mutation of the CSF1R gene. The CSF1R gene is autosomal dominant, which means that just one copy of the mutated gene from either parent is enough to cause the disease.

A person who has the CSF1R gene mutation has a 50% chance of passing the gene on to each child, regardless of their sex. All individuals who carry the CSF1R gene mutation have a 50% chance of passing the mutation  on to their children.

Since the onset of ALSP symptoms usually occurs later in life, the disease is often diagnosed after the childbearing years, when many individuals have already had children.

With genetic testing, individuals can find out whether they have the CSF1R mutation before developing symptoms or before there is evidence of disease through brain imaging and other tests. Individuals who have a confirmed genetic mutation but have no symptoms of ALSP may be referred to as “carriers” or “pre-symptomatic.” Individuals who carry the mutation will most likely develop ALSP.

Since ALSP symptoms are similar to other diseases, especially other leukodystrophies, it can often be misdiagnosed. Genetic testing to identify a CSF1R mutation can be an important step in confirming an ALSP diagnosis. Testing early allows individuals, caregivers and families to better prepare for the future.