Happy 70th Birthday Stephen Hawking!

Today is Stephen Hawking’s 70th birthday!

Not an insignificant feat for someone who has been dealing with a serious illness for most of his life.

Beginning at age 21, the British physicist and mathematician has experienced progressive loss of muscle function, leaving him nearly completely paralyzed and only able to communicate through a computerized voice (which he jokes “gives him an American accent”).

Despite his disability, Professor Hawking has had a long and distinguised career studying “black holes” and other remarkable features of the universe. Unlike many scientists, he is also a gifted communicator of scientific concepts and is the author of several books, including some for children.

In recognition of Hawking’s upcoming 70th birthday, the Centre for Theoretical Cosmology, University of Cambridge, is hosting a symposium entitled “The State of the Universe” on January 8. In addition, an exhibition of his life and work will open at the Science Museum, London, on January 20.

Although it is frequently reported that Hawking suffers from Amoytrophic Lateral Sclerosis (ALS), or Lou Gehrig Disease, most medical experts believe that what he actually suffers from is a related illness called Spinal Muscular Atrophy (SMA).

Both ALS and SMA are just two of a group of disorders, called Motor Neuron(e) Diseases (MND), where nerve cells that control muscles are damaged. Muscle cells depend on stimulation from nerves to function, and without this stimulation, muscle cells weaken or die. This leads to the classic symptoms of progressive muscle weakness. In both diseases, mental functioning remains normal.

But there are major differences between the two diseases:

Spinal Muscular Atrophy

Spinal Muscular Atrophy occurs when a “survivor motor neuron” gene is deleted or mutated, preventing the creation of a protein necessary for muscle strength. This disease varies in severity; the younger the age of onset, the more severe the symptoms. Infants with the disease most likely die before two years of age. Adult onset is associated with a much better prognosis, and the potential for a normal life expectancy. The most common types include:

SMA type I, also called Werdnig-Hoffmann disease, is noticeable by the time a child is 6 months old. Symptoms may include severely decreased muscle tone, decreased arm and leg movements, absence of reflexes, tremors, swallowing and feeding difficulties, and difficulty breathing. Some children also develop scoliosis (curvature of the spine) or other skeletal abnormalities. Affected children never sit or stand and the vast majority usually die of respiratory failure before the age of 2.

Symptoms of SMA type II usually begin after the child is 6 months of age. Features may include inability to stand or walk, respiratory problems, low muscle tone, and decreased or absent reflexes. These children may learn to sit but do not stand. Life expectancy varies, and some individuals live into adolescence or later.

Symptoms of SMA type III (Kugelberg-Welander disease) appear between 2 and 17 years of age and include abnormal gait; difficulty running, climbing steps, or rising from a chair; and a fine tremor of the fingers. The lower extremities are most often affected. Complications include scoliosis and joint contractures—chronic shortening of muscles or tendons around joints, caused by abnormal muscle tone and weakness, which prevents the joints from moving freely.

Amyotrophic Lateral Sclerosis

On the other hand, it is unknown what causes Amyotrophic Lateral Scherosis. It most frequently occurs in adults over 40.

Symptoms are usually noticed first in the arms and hands, legs, or swallowing muscles. Affected individuals lose strength and the ability to move their arms, legs, and body.

Other symptoms include spasticity, muscle cramps, and increased problems with swallowing and forming words. Speech can become slurred or nasal.

When muscles of the diaphragm and chest wall fail to function properly, individuals lose the ability to breathe without mechanical support. Most patients die within 3 to 5 years from the onset of symptoms.

Although the disease does not usually impair a person’s mind or personality, several recent studies suggest that some people with ALS may have alterations in cognitive functions such as problems with decision-making and memory.

Organizations such as the Muscular Dystrophy Association and the National Institute of Neurological Diseases and Stroke support a broad range of research aimed at discovering the cause(s) of MNDs, finding better treatments, and, ultimately, preventing and curing the disorders.

Various MND animal models (animals that have been designed to mimic the disease in humans) are being used to study disease pathology and identify chemical and molecular processes involved in cellular degeneration. Both diseases may eventually be treated or cured by research involving new drugs, growth factors and stem cell therapy.