Amyotrophic Lateral Sclerosis (ALS)/Lou Gehrig's Disease

Home » Amyotrophic Lateral Sclerosis (ALS)/Lou Gehrig's Disease » Risk Factors, Causes

Questions to Ask Your Doctor about ALS
(Free Handout)

Risk Factors

Risk factors include an inherited genetic defect, which accounts for 5–10% of cases of familial ALS (FALS) in the United States. FALS is linked to a genetic defect on chromosome 21. This gene codes for an enzyme called superoxide dismutase (SOD), an antioxidant that protects motor neurons from free radical damage (i.e., molecules introduced to the body, or produced by body processes that interact and cause cellular damage). More than 60 different mutations that cause SOD to lose its antioxidant properties have been found. However, only 40% of familial ALS cases are linked to SOD mutations, so there may be other unknown genetic defects involved.

In the United States, 90–95% of ALS cases are sporadic. Sporadic ALS appears to be increasing worldwide. The causes are not clear, yet some evidence suggests that the immune system may be involved. Excessive levels of glutamate can overstimulate motor neurons and cause them to die. Glutamate is one of the most important neurotransmitters for healthy brain function. Neurotransmitters are chemicals that transmit signals from one nerve to another.

In Guamanian ALS, a dietary neurotoxin is the risk factor. The suspected neurotoxin is an amino acid (BMAA) found in the seed of the cycad Cyas cirinalis, a tropical plant found in Guam, which was used to make flour and was a major dietary component during the 1950s and the early 1960s, when this type of ALS had an exceptionally high incidence.

Causes

The cause of ALS is not completely understood. Researchers and physicians suspect viruses, neurotoxins (especially in Guamanian ALS), heavy metals, DNA defects (especially in familial ALS), immune system abnormalities, and enzyme abnormalities.

© 1998-2010 Healthcommunities.com, Inc. All Rights Reserved.

Amyotrophic Lateral Sclerosis (ALS)/Lou Gehrig's Disease Resources

	Join Our ALS Forum Do you have a question, want to share medical advice, or just need to discuss your situation with someone else having a similar experience? The healthchannels forum is a resource for everyone to share and discuss their health and medical needs with others.	Advertising Disclaimer
	Living with...Share your story Do you have a personal health story that you would like to share with others? As a source of free patient education, our goal is to provide our users with trustworthy information and support from others. That's why we've started our "Living with..." sections.
	Our "Living With..." support pages are a place to share experiences about living with a certain condition, disease, disorder, or illness and for loved ones of those dealing with health-related issues. Many people, especially when newly diagnosed, find comfort in knowing that others are having a similar experience. Help others by sharing your story. View stories already submitted.
	Stay Updated Sign up for our newsletter and receive important updates on the medical conditions that are most important to you.
To quickly access health information from your website's browser, download Healthcommunities.com's healthchannels toolbar.