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.

Source: MedTerms™ Medical Dictionary
http://www.medterms.com/script/main/art.asp?articlekey=34043
Last Editorial Review: 7/12/2004