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Medical Author:

Fernando Dangond, MD

Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Amyotrophic Lateral Sclerosis Causes

We do not know exactly what causes ALS. Although about 10% of cases of ALS are hereditary (run in families), the other 90% are not. A mutation of a gene called SOD1 has been identified in some of the hereditary cases, but we do not know what role the mutation plays in the disease.

Using an evidence-based approach, smoking was found to be more likely than not a risk factor for ALS based on two excellent studies by Kamel et al. and Nelson et al. Smoking has a broad public health impact, no redeeming features, and is a modifiable risk factor. Evidence also supported the conclusion that the following were probably not risk factors for ALS: trauma, physical activity, residence in rural areas, and alcohol consumption.