Autosomal recessive distal hereditary motor neuropathy

Autosomal recessive distal hereditary motor neuropathy (AR dHMN) is a rare inherited neuromuscular disorder characterized by progressive weakness and wasting (atrophy) of the distal muscles, primarily affecting the hands and feet. Unlike some other peripheral neuropathies, sensory function is typically preserved or only minimally affected, as the disease predominantly impacts the lower motor neurons. The condition belongs to the broader group of distal hereditary motor neuropathies (dHMN), which are genetically heterogeneous disorders distinguished by their inheritance pattern and specific genetic causes. Patients with AR dHMN typically present with progressive difficulty in walking, foot drop, and weakness in the lower legs, which may later extend to the hands and forearms. Muscle wasting in the distal limbs is a hallmark feature, and affected individuals may develop foot deformities such as pes cavus (high-arched feet) or hammer toes. Deep tendon reflexes are often reduced or absent in the affected limbs. The age of onset can vary but frequently begins in childhood or adolescence, with a slowly progressive course. The severity of disability varies among affected individuals, even within the same family. There is currently no cure or disease-modifying treatment for autosomal recessive distal hereditary motor neuropathy. Management is supportive and symptomatic, focusing on physical therapy and rehabilitation to maintain mobility and muscle strength, orthotic devices (such as ankle-foot orthoses) to assist with walking, and occupational therapy to help with fine motor tasks. Surgical intervention may be considered for significant skeletal deformities. Genetic counseling is recommended for affected families to understand recurrence risks and facilitate family planning decisions.

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