ALS will eventually spread to other parts of the body, but will most often start in the feet, hands, or limbs. Muscles will progressively atrophy as the disease advances. ALS doesn’t typically affect thinking ability, bowel or bladder control, or senses. In some ALS cases the disease is hereditary, while the others remain with no known cause. Researchers are also looking into protein mishandling, chemical imbalances, gene mutation, and disorganized immune responses. Research is also being done into cellular defects, stem cells, family versus sporadic ALS, biomarkers, and new treatment