Distal hereditary motor neuropathy type V

Charcot-marie-tooth foot

Distal hereditary motor neuropathy type V (dHMN V) is a rare genetic disorder that primarily affects the motor neurons in the peripheral nervous system. This condition is characterized by progressive muscle weakness and atrophy, particularly in the distal parts of the limbs, such as the hands and feet.

Clinical Features

Individuals with dHMN V typically present with symptoms in late childhood or early adulthood. The primary clinical features include:

• Progressive muscle weakness and atrophy in the hands and feet
• Difficulty with fine motor skills, such as buttoning clothes or writing
• Foot deformities, such as pes cavus (high-arched feet)
• Mild to moderate sensory loss in the affected areas

Genetics

dHMN V is inherited in an autosomal dominant manner. Mutations in the BSCL2 gene have been identified as a cause of this condition. The BSCL2 gene provides instructions for making a protein called seipin, which is involved in the development and maintenance of motor neurons.

Diagnosis

The diagnosis of dHMN V is based on clinical evaluation, family history, and genetic testing. Electromyography (EMG) and nerve conduction studies (NCS) are often used to assess the function of the peripheral nerves and muscles.

Differential Diagnosis

dHMN V should be differentiated from other types of hereditary motor neuropathies, such as:

• Charcot-Marie-Tooth disease
• Spinal muscular atrophy
• Other subtypes of distal hereditary motor neuropathy

Management

There is currently no cure for dHMN V. Management focuses on symptomatic treatment and supportive care, including:

• Physical therapy to maintain muscle strength and flexibility
• Occupational therapy to assist with daily activities
• Orthopedic interventions for foot deformities
• Pain management, if necessary

Prognosis

The progression of dHMN V is typically slow, and life expectancy is generally not affected. However, the degree of disability can vary widely among affected individuals.

See Also

• Hereditary motor and sensory neuropathy
• Peripheral neuropathy
• Neurogenetic disorders

References

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