Is ALS Genetic?
There are two general classifications of ALS, Sporadic and Familial. Although the exact causes for sporadic ALS are still unclear, familial ALS is passed on genetically.
About 10 percent of cases are classified as hereditary or Familial ALS (fALS). Although clinically indistinguishable from Sporadic ALS, Familial ALS or fALS is inherited through an autosomal dominant gene mutation. When we are born, we get one copy of DNA from each parent, but normally only one of these genes expresses itself. The expressed gene is considered the more dominant gene. An autosomal dominant gene is the gene that will always be expressed in a carrying individual. There are several different genes that have been associated with fALS. The first discovered gene is SOD1, which comprises 12 percent of fALS cases. Because there are so many different genes, most cases are not tested for fALS unless there is known history of the disease in the patient's family.