Alternative Names
ALS; Lou Gehrig's disease; Charcot disease
Symptoms & Characteristics
Amyotrophic lateral sclerosis (ALS), commonly known as Lou Gehrig's disease, is a nervous system disease that attacks motor neurons in the brain and the spinal cord. Motor neurons are responsible for coordinating signals between the brain and spinal cord and muscles to control movement. In the beginning, this causes mild muscle problems, like walking or writing. Eventually, the problems worsen and an affected person cannot move or breathe.
Symptoms of the disease usually appear between age 40 and 60. ALS can run in families with more than one affected family member, called familial ALS (FALS), but typically strikes at random with no family history, called sporadic ALS (SALS). FALS and SALS are clinically similar. However, most people with SALS have symptom onset at about 56 years old, while most people with FALS have symptom onset at about 46 years old.
Management & Treatment
Early diagnosis, routine surveillance, and treatment of ALS may help to manage some of the symptoms. Individuals with ALS may benefit from care by a multidisciplinary team that includes a neurologist, specially trained nurses, pulmonologist, speech therapist, physical therapist, occupational therapist, respiratory therapist, nutritionist, psychologist, social worker, and genetics professional.
Riluzole is currently the only FDA-approved drug for treatment of ALS.
Medications may be offered for extra saliva or drooling. Antidepressants may be offered to help manage emotional lability. Medications, such as baclofen and benzodiazepines, may help relieve spasticity and muscle cramps.
Swallowing difficulties may be alleviated by thickening liquids and pureeing solid food and, eventually, by use of a gastrostomy tube to help maintain caloric intake and hydration.
Assistive devices, such as walkers, wheelchairs, bathroom modifications, hospital beds, and hoyer lifts can aid in activities of daily life. Breathing devices and computer-assisted speaking devices may also be needed.
How Common Is It?
About 30,000 people are affected with ALS in the United States. More men than women are typically affected.
Genetics & Inheritance
The cause of SALS is largely unknown.
Sporadic ALS is most likely multifactorial condition, which means that it involves a combination of genetic, lifestyle and environmental factors.
- Many environmental factors have been proposed to possibly contribute to ALS, including (but not limited to): mercury, manganese, formaldehyde, farming chemicals (fertilizers, insecticides, herbicides); as well as physical and dietary factors.
Familial ALS makes up about 10% of total cases of ALS. Different types of FALS are distinguished by their genetic cause, the age at which symptoms began (age of onset), and disease progression (slow or fast). Although 9 types of ALS have currently been identified, only a small percentage of cases have actual known genes and established patterns (modes) of inheritance. As of yet, researchers have only adequately identified and classified genetic mutations that cause ALS types 1, 2, 4, and 8.
|
FALS Genetics
|
| Type |
Gene |
Location* |
| Type 1 |
SOD1 |
21q22.1 |
| Type 2 |
ALS2 |
2q33.2 |
| Type 4 |
SETX |
9q34.3 |
| Type 8 |
VAPB |
20q13.33 |
| *indicates chromosome number and gene location |
We all have two copies of each of above genes - one from each parent. The pattern of inheritance of FALS varies by type.
- In types 1, 4 and 8, having a mutation in a single gene copy is sufficient to cause the disease. However, not every person who has a mutation will develop physical symptoms in their lifetime. This is called autosomal dominant inheritance with incomplete penetrance. Every person with a mutation has a 50% chance to pass on their mutation to each child they have.
- In type 2, and some cases of type 1, it is necessary to have two mutations, one in each copy, to be affected. This is called autosomal recessive inheritance. Both parents of affected people are always obligate carriers (each have only one mutation). Two carriers have a 25% chance in each pregnancy to have an affected child, but do not have symptoms themselves.
In addition, some genes do not cause ALS, but instead have been associated with an increased risk (or susceptibility) to develop ALS.
- Mutations in a number of other genes including, ANG, DCTN1, NEFH, or PRPH genes appear to increase the risk to develop ALS.
- Some studies suggest that a decrease in the number of SMN1 or SMN2 genes may also lead to an increased susceptibility to or severity of ALS, but exactly how is unclear at this time.
Not all genes that cause ALS or cause susceptibility to ALS are known at this time.
There are other genetic and non-genetic conditions, which have symptoms that overlap with ALS. As such, a genetic consultation with a trained genetic professional may be beneficial for a complete evaluation and accurate diagnosis.
Genetic Testing
Clinical genetic testing for ALS (types 1, 2, 4, and 8) may be available through genetic consultation for people who are considered at risk. A trained genetic professional can discuss the benefits and limitations of genetic testing for ALS, coordinate testing and interpret results in the context of personal and family medical history.
- A board-certified genetic counselor is available by telephone.
Informational genetic testing for susceptibility to ALS is available online (over the internet) as part of a whole genome scan. Whole genome scanning involves analyzing thousands of SNPs at once related to a number of different health conditions.
- At this point, many genetic professionals do not consider this testing clinically useful or medically relevant, but for informational purposes only. Go to the Tests tab to link to the best providers, compare providers and read provider reviews.
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