Distal spinal muscular atrophy type 2

Not to be confused with Distal spinal muscular atrophy.

Distal spinal muscular atrophy type 2 (DSMA2), also known as hereditary motor neuropathy type II, is a rare genetic disorder characterized by progressive muscle weakness and atrophy, primarily affecting the distal muscles of the limbs. This condition is part of a group of disorders known as spinal muscular atrophies (SMAs), which are caused by the degeneration of motor neurons in the spinal cord.

Clinical Features

Individuals with distal spinal muscular atrophy type 2 typically present with muscle weakness and wasting that begins in the hands and feet. The onset of symptoms usually occurs in childhood or early adulthood. The progression of the disease is generally slow, and the severity can vary among affected individuals.

Symptoms

• Muscle weakness in the hands and feet
• Muscle atrophy
• Difficulty with fine motor skills
• Foot deformities such as high arches or flat feet
• Hand deformities
• Mild sensory loss in some cases

Diagnosis

The diagnosis of DSMA2 is based on clinical evaluation, family history, and genetic testing. Electromyography (EMG) and nerve conduction studies may be used to assess the function of the peripheral nerves and muscles. Genetic testing can confirm the diagnosis by identifying mutations in the genes associated with the condition.

Genetics

Distal spinal muscular atrophy type 2 is inherited in an autosomal dominant manner, meaning that a single copy of the altered gene in each cell is sufficient to cause the disorder. The specific gene mutations responsible for DSMA2 have been identified in some cases, but the genetic basis of the condition is not fully understood.

Pathophysiology

The underlying cause of muscle weakness and atrophy in DSMA2 is the degeneration of motor neurons in the anterior horn of the spinal cord. This leads to a loss of nerve signals to the muscles, resulting in muscle wasting and weakness.

Management

There is currently no cure for distal spinal muscular atrophy type 2. Management focuses on alleviating symptoms and improving quality of life. This may include:

• Physical therapy to maintain muscle strength and flexibility
• Occupational therapy to assist with daily activities
• Orthopedic interventions for foot and hand deformities
• Assistive devices such as braces or splints

Prognosis

The prognosis for individuals with DSMA2 varies depending on the severity of the condition. While the disease is progressive, many individuals maintain a good quality of life with appropriate management and support.

Related Pages

• Spinal muscular atrophy
• Motor neuron disease
• Peripheral neuropathy