Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, is a progressive neurodegenerative disease. It is characterized by the destruction of motor neurons or nerve cells that control muscle movement, leading to disability.
Incidence of ALS
The average incidence rate of ALS worldwide is about one in 50,000 people per year that equates to about 5,760 to 6,400 new diagnoses per year.
The average age of onset of the disease is about 60 years, with men at a slightly higher risk compared to women (a male-to-female ratio of 1.5 to 1). However, with advancing age, the gender gap narrows considerably.
ALS is reported to have higher incidence rates among Caucasians (93%) and non-Hispanics compared to other ethnic groups. However, since ALS is a non-notifiable disease (not required by law to be reported officially to health authorities), it is likely that not all cases have been recorded in the National ALS Registry.
Prevalence of ALS
The prevalence of ALS is about one in 20,000 at any given time in Western countries and this has remained relatively unchanged in recent years. Those with a family history of ALS and who are 60 or older are likely to develop the disease.
According to the Agency for Toxic Substances and Disease Registry (ATSDR), the lowest prevalence was observed in people age 18 to 39 (0.5 per 100,000 individuals), while those age 70 to 79 had the highest prevalence rate (20 per 100,000 individuals).
Whites, men, certain occupations, nutritional intake, exposure to infections, physical activity, and trauma are other risk factors.
Etiology
Most cases of ALS (about 90%) are sporadic, i.e., occuring spontaneously without a known family history or associated environmental risk factors. About 5 to 10% of the cases are familial, and among these, the prevalence for different gene mutations associated with the disease are as follows:
- C9ORF72 gene — 25 to 40% of cases
- SOD1 gene — 12 to 20% of cases
- TARDBP gene — 2 to 5% of cases
- FUS gene — 5% of cases
- VCP gene — 1 to 2% of cases
Most cases of familial ALS are inherited in an autosomal dominant manner. However, autosomal recessive and X-linked inheritance patterns also are possible.
Last updated: Sept. 28, 2019
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