What is “familial” ALS?

Familial” ALS (“FALS” for short) is a hereditary form of ALS. In FALS, genetic changes (“hereditary factors”) cause ALS, which is inherited within the family, usually over generations. The most common constellation of FALS is that a family member with the disease is already known in the parents’ or grandparents’ generation. It is rarer for siblings to have the disease without the parents having had the disease beforehand. FALS is always to be suspected if more than one person within the descendants of a family has ALS or has died. FALS may also be present if one family member has ALS but at least one other family member has been diagnosed with frontotemporal dementia.

ALS and FTD are diseases that (despite different symptoms) have a similar disease mechanism and can be caused by common genes. Genetic changes are known that can cause ALS in one family member and FTD or a combination of ALS and FTD in another family member. Therefore, when determining a family tree, it is important to find out whether dementia has been described in the family in addition to paralytic diseases. However, a distinction must be made here from the very common Alzheimer’s dementia, which is a widespread disease and bears no relation to ALS. FTD is a special form of dementia that usually occurs at a younger age and is associated with behavioral abnormalities and changes in character. If there are indications of FALS, consultation with a specialist in human genetics is recommended. After a human genetics consultation, the doctor and patient should decide together whether molecular genetic diagnostics of ALS genes is possible and appropriate.

The detection of genetic changes (mutations) objectifies the diagnosis of FALS and enables a more concrete risk assessment for the next generation. With the approval of gene therapy drugs aimed at correcting mutations, genetic diagnostics is also becoming therapeutically relevant for those affected.