Handbook of Genetic Counseling/Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS)

What is ALS?Edit

  • a degenerative disease of the nervous system, affecting the brain cells (motor neurons) that carry impulses from the brain and spinal cord to the muscles
  • results in muscular weakness and the progressive wasting of muscles that have lost their nerve supply
  • the most common form of motor neuron disease
  • patients have difficulty speaking, swallowing, and breathing
  • death usually follows within 3 to 5 years
  • onset commonly occurs between the ages of 35 and 65
  • slightly more common in men than in women
  • 5-10% of ALS cases are familial
  • The gene is inherited as an autosomal dominant genetic trait and is located on the long arm of chromosome 21
  • 90% of ALS cases are sporadic, with no obvious genetic cause
  • manifests differently amongst patients, likely due to environmental agents interacting with genetic susceptibility
  • ALS strikes 2 to 7 out of every 100,000 people in the USA
  • no specific treatment yet exists, and patients can be aided only by supportive therapy
  • ALS is also called Lou Gehrig's disease after the baseball star who died of it


  • early symptoms include slight muscle weakness, clumsy hand movements, and/or difficulty performing tasks that require delicate movements of the fingers and/or hands
  • muscular weakness in the legs may cause tripping and falling
  • difficulty swallowing (dysphagia)
  • speech may be slowed
  • progressive weakness of the lips and impairment and/or loss of function of the tongue, mouth, and/or voice box (bulbar symptoms)
  • leg cramps may occur during the night, most frequently in the calf and/or thigh muscles
  • uncontrolled twitching of muscles (fasciculations)
  • exaggerated deep muscle reflexes.
  • severe weight loss occurs in approximately 5% of cases
  • increased risk for respiratory failure and abnormally low levels of oxygen in the blood
  • increased risk for acute inflammation of the lungs, caused by the inhalation of food or stomach contents (aspiration pneumonia).
  • an overall decrease in the ability to move may also result in inadequate nutrition

Resources and Support GroupsEdit

  • The ALS Association
the only national not-for-profit health agency dedicated to the fight against ALS
the mission of The ALS Association (ALSA) is to find a cure for and improve living with amyotrophic lateral sclerosis
toll-free information and referral service available to patients, caregivers and family members, staffed by ALSA Patient Service Co-ordinators.
1-800-782-4747 (Monday through Friday 7:30am to 4:00pm PST)
to reach ALSA's Patient Services department by e-mail, contact alsinfo@alsa-national.org.
Suite 150
27001 Agoura Road
Calabasas Hills, CA 91301
(818) 880-9007
  • NIH/National Institute of Neurological Disorders & Stroke (NINDS)
9000 Rockville Pike
Bethesda MD 20892
(301) 496-5751
(800) 352-9424
  • ALS Canada: [2]
  • ALS Society of British Columbia: [3]


The information in this outline was last updated in 2002.