Genetic Causes of ALS
Causes of ALS
ALS is classified into two categories:
ALS is classified into two categories:
- Sporadic (90-95% of all cases), which means they don't know the cause
- Familial (5-10% of all cases) which are inherited genetically
Familial causes
Within Familial causes, there are 4 known genes that can cause ALS:
Within Familial causes, there are 4 known genes that can cause ALS:
- C9ORF72
- Name refers to the location of the gene on chromosome 9.
- Research now theorizes it is inherited in a dominant manner
- Mutations in this gene account for 25-40% of all familial cases.
- How the mutation causes ALS is still being researched and is unknown
- Cu/Zn Superoxide Dismutase 1(SOD1)
- Gene is found in chromosome 21
- This gene is inherited in a dominant manner
- Mutations in this gene account for ~10% of all familial cases
- How the mutation causes ALS is also unknown.
- Believed it is not caused from a not from a non-functioning protein because removing the gene in animals does not produce ALS.
- TAR DNA Binding Protein 43 (TDP 43)
- Gene is found in chromosome 1.
- Inherited in a dominant manner.
- Mutations in this gene cause the protein to relocate into the cytoplasm instead of the nucleus, causing clumps
- How these clumps cause ALS isn't completely know but research suggests there is a relationship
- Fused in Sarcoma (FUS)
- Located on chromosome 23, the X chromosome.
- Inherited in a dominant manner.
- Normal protein function is to destroy or clear out damaged or non-functioning proteins.
- Research suggests that a mutation in this gene may cause this function to stop leading to the build up of harmful material in the cell.