What is amyotrophic lateral sclerosis (ALS) (Lou Gehrig disease)?

Updated: Apr 28, 2014
  • Author: Hidehiro Takei, MD; Chief Editor: Adekunle M Adesina, MD, PhD  more...
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ALS, also known as Lou Gehrig disease, is the most common neurodegenerative disease of adult onset involving the motor neuron system. It is a fatal disorder and is characterized by progressive skeletal muscle weakness and wasting or atrophy (ie, amyotrophy), spasticity, and fasciculations as a result of degeneration of the UMNs and LMNs, culminating in respiratory paralysis. There are 3 types of ALS, as follows:

  • Sporadic ALS

  • Familial ALS

  • Western Pacific ALS with or without Parkinsonism-dementia complex (ALS/PDC)

Most ALS cases are sporadic, and only 5-10% of cases are considered to be familial. Mutations in the C9orf72 gene are responsible for 30-40% of familial ALS cases in the United States and Europe. Worldwide, approximately 20% of cases of familial ALS are due to a mutation in the Cu/Zn superoxide dismutase–1 gene (SOD1). Western Pacific ALS occurs on the islands of Guam (Guam ALS), on the Kii peninsula of Japan, and in Western New Guinea. It is now clear that a subset of ALS cases shows features of frontotemporal lobar degeneration (FTLD) (ie, FTLD-MND/ALS).

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