Definition of Familial ALS

Familial ALS: ALS (amyotrophic lateral sclerosis) in which there a family history of the disease. Familial ALS constitutes 5 to 10% of all cases of ALS. There are a number of different types of familial ALS.

They are known as ALS1, ALS2, and so on.

• ALS1 -- caused by mutation in the superoxide dismutase-1 gene (SOD1) on chromosome 21q22.1. About 15 to 20% of familial ALS is type 1 (ALS1). Sporadic cases of ALS are sometimes due to new mutation in the SOD1 gene.
• ALS2 -- juvenile-onset ALS caused by mutation in the gene encoding alsin on chromosome 2q33;
• ALS3 -- adult-onset ALS due to mutation in a gene on chromosome 18q21;
• ALS4 -- juvenile-onset disease with no bulbar involvement due to mutations in a gene on chromosome 9q34;
• ALS5 -- due to mutations in a gene on chromosome 15q15.1-q21.1;
• ALS6 -- due to mutations in a gene on chromosome 16q12;
• ALS7 -- due to mutations in a gene on chromosome 20ptel;
• ALS8 -- due to mutations in a gene on chromosome 20q13.33.

ALS1, ALS3, ALS4, ALS6, ALS7, and ALS8 are inherited in an autosomal dominant manner while ALS2 and ALS5 are inherited in an autosomal recessive manner.

Last Editorial Review: 7/12/2004

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