**Most ALS has no known cause, but inherited gene changes cause some cases.**
ALS, or amyotrophic lateral sclerosis, damages nerve cells that control your voluntary muscles. Most people who develop ALS have no known family history of it. If ALS runs in your family, a clinician or genetic counselor can explain what that means for you. Record any persistent changes in your strength, walking, or speech and discuss them with your clinician. MedlinePlus and the CDC offer information you can use to prepare for that conversation.
Understanding what causes ALS
Common questions
What causes ALS - resources?
Most ALS has no known cause; inherited gene changes explain some cases. ALS damages nerve cells that control voluntary muscles, but most people who develop it have no known family history. Your symptoms or family history alone cannot establish a diagnosis. See a clinician for progressive weakness or persistent changes in walking, speech, or swallowing. Ask about genetic counseling if ALS runs in your family. For reliable resources, use MedlinePlus for an overview and the CDC National ALS Registry for research information and links to support organizations.