Amyotrophic Lateral Sclerosis 11

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2019-09-22
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A number sign (#) is used with this entry because this form of autosomal dominant ALS is caused by mutation in the FIG4 gene (609390).

Autosomal recessive Charcot-Marie Tooth disease type 4J (CMT4J; 611228) is an allelic disorder with a much more severe phenotype.

For a general phenotypic description and a discussion of genetic heterogeneity of amyotrophic lateral sclerosis (ALS), see ALS1 (105400).

Clinical Features

Chow et al. (2009) reported 5 unrelated patients diagnosed with probable or definite ALS. Two had a family history of the disorder. All had adult onset and showed prominent corticospinal tract findings. Nerve conduction velocity studies were normal, but EMG studies showed some denervation.

Molecular Genetics

In 5 unrelated patients with amyotrophic lateral sclerosis, Chow et al. (2009) identified heterozygosity for a missense, 2 splice site, and 2 truncating mutations in the FIG4 gene (see, e.g., 609390.0006-609390.0008). The mutations were shown to result in complete or highly significant loss of protein function. Five different missense FIG4 mutations were identified in 5 patients with a diagnosis of ALS or adult-onset primary lateral sclerosis (PLSA1; 611637), but these mutations were not clearly shown to be pathogenic.