Amyotrophic Lateral Sclerosis 19

Watchlist
Retrieved
2019-09-22
Source
Trials
Genes
Drugs

A number sign (#) is used with this entry because amyotrophic lateral sclerosis-19 (ALS19) is caused by heterozygous mutation in the ERBB4 gene (600543) on chromosome 2q34.

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

Clinical Features

Takahashi et al. (2013) reported 3 Japanese sibs with onset of classic ALS between 60 and 70 years of age. They had relatively slowly progressive upper and lower motor neuron involvement without cognitive impairment. Two patients became ventilator-dependent and all 3 developed the locked-in state. Their deceased father was reportedly affected, but was not examined. An unrelated individual of Canadian origin had a similar disorder, with a positive family history. An additional Japanese proband with sporadic ALS showed earlier onset at 45 years of age and became wheelchair-bound.

Inheritance

The transmission pattern of ALS in the families reported by Takahashi et al. (2013) was consistent with autosomal dominant inheritance, and the authors postulated incomplete penetrance.

Molecular Genetics

In 3 Japanese sibs with late-onset amyotrophic lateral sclerosis-19, Takahashi et al. (2013) identified a heterozygous missense mutation in the ERBB4 gene (R927Q; 600543.0001). The mutation was found by whole-genome sequencing after exclusion of mutations in several known ALS-associated genes, and was consistent with linkage analysis. Sequencing of the ERBB4 gene in 364 familial ALS and 818 sporadic ALS cases identified 1 Canadian individual with familial ALS who also carried the same heterozygous R927Q mutation and a Japanese individual with sporadic ALS who carried a different de novo heterozygous missense mutation (R1275W; 600543.0002). The patients with the R927Q mutation had onset of classic upper and lower motor neuron degeneration between 60 and 70 years of age, whereas the patient with the R1275W mutation had earlier onset at age 45. In vitro functional expression studies in COS-7 cells showed that the mutant ERBB4 proteins had decreased autosphosphorylation upon NRG1 (142445) stimulation compared to wildtype. The findings suggested that disruption of the neuregulin-ERBB4 pathway is involved in the pathogenesis of ALS.