INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects nerve cells in the brain and spinal cord. Motor neurons enable communication between the brain and the spinal cord and between the spinal cord to the muscles of the body. The progressive degeneration of the motor neurons in ALS eventually results in the ability of the brain to initiate and control muscle movement. With voluntary muscle action progressively affected, patients in the later stages of the disease may become totally paralyzed, while their minds remain unaffected.

Early symptoms of ALS include increasing muscle weakness, especially in the muscles involving the arms and legs, speech, swallowing or breathing. When muscles no longer receive the input they require from the motor neuron, the muscles begin to atrophy and the limbs appear thinner.

Three classifications of ALS have been made:

• Sporadic - the most common form of ALS - 90 to 95% of all cases.
• Familial - occurring more than once in a family lineage (genetic dominant inheritance) accounts for a very small number of cases - 5 to 10% of all cases.
• Guamanian - an extremely high incidence of ALS was observed in Guam and the Trust Territories of the Pacific in the 1950's.

The most common form of ALS is "sporadic" ALS. It may affect anyone, anywhere. "Familial" ALS (FALS) means the disease is inherited. Only about 5 to 10% of all ALS patients appear to have genetic or inherited form of ALS. In those families, there is a 50% chance each offspring will inherit the gene mutation and may develop the disease.