Distal hereditary motor neuropathies

Distal hereditary motor neuropathies (distal HMN, dHMN) are a genetically and clinically heterogeneous group of motor neuron diseases that result from genetic mutations in various genes and are characterized by degeneration and loss of motor neuron cells in the anterior horn of the spinal cord and subsequent muscle atrophy.

Even though they can hardly be distinguished from hereditary motor and sensory neuropathies on the clinical level, dHMNs are a considered a separate class of disorders.

Classification
In 1993, A. E. Hardnig proposed to classify hereditary motor neuropathies into seven groups based on age at onset, mode of inheritance, and presence of additional features. This initial classification has since been widely adopted and expanded and currently looks as follows: