Hereditary motor and sensory neuropathies progressively debilitate leg and arm movement and impair sensation. The wide variability in symptoms and genetic etiology, as well as the lethality of known mutations in mice, has delayed the development of model organisms. Francesca Achilli and colleagues made a dominant mutation in glycyl-tRNA synthetase (GARS), which appears in some cases of familial Chariot-Marie-Tooth (CMT) and infantile hereditary motor neuropathy (HMN). The mice have muscle weakness, loss of electrical conduction in neurons, and neuromuscular junction defects. An increasing number of nervous system diseases are linked with tRNA synthetase mutations, and this model should help determine the role of protein translation in these and other similar diseases.

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