Distal hereditary motor neuropathy, type II
Distal hereditary motor neuropathy, type II is a progressive disorder that affects nerve cells (neurons) in the brain and spinal cord. This condition specifically affects motor neurons, which are specialized cells that control muscle movement. Damage to motor neurons results in muscle weakness that worsens over time. Distal hereditary motor neuropathy, type II weakness primarily affects movement in the legs.
The signs and symptoms of distal hereditary motor neuropathy, type II often begin in adolescence to mid-adulthood. The initial symptoms of the disorder are cramps or weakness in the muscles of the big toe and, later, the entire foot. During the next 5 to 10 years, affected individuals experience a gradual loss of muscle tissue (atrophy) in the lower legs, which can lead to problems with walking (gait disturbance) and high arches (pes cavus). Over time, the lower legs may become paralyzed. The thigh muscles may also undergo muscle atrophy, although this generally occurs later and is less severe than the muscle atrophy in the lower legs.
Some individuals with distal hereditary motor neuropathy, type II can also experience weaken the muscles in the hands and forearms. This weakening is less severe than the weakening in the lower limbs and does not usually lead to paralysis. In rare cases, affected individuals experience hearing loss.
People with distal hereditary motor neuropathy, type II can have exaggerated reflexes (hyperreflexia) or other minor disturbances in the nerves used to detect sensations (sensory neuropathy). Sensory neuropathy is uncommon in people with distal hereditary motor neuropathy, type II and is typically a feature of a disorder calledCharcot-Marie-Tooth disease. These two disorders have overlapping features and can also share a genetic
Other names
Distal hereditary motor neuronopathy, type II; HMN II; HMN2; HMND2
Inheritance pattern
Autosomal dominant
Related genes
HSPB1; HSPB8; HSPB3; FBXO38
Source: MedlinePlus Genetics, U.S. National Library of Medicine.
