Spinal muscular atrophy with lower extremity predominance 2A

Spinal Muscular Atrophy with Lower Extremity Predominance 2A (SMA-LED2A), also known as autosomal dominant spinal muscular atrophy 2 (DSMA2), is a rare neuromuscular disorder characterized by muscle weakness and atrophy predominantly affecting the lower limbs. SMA-LED2A is a form of spinal muscular atrophy (SMA), a group of genetic disorders that result in muscle wasting and weakness. Unlike the more common forms of SMA, which are typically inherited in an autosomal recessive manner, SMA-LED2A is inherited in an autosomal dominant fashion.

Genetics

SMA-LED2A is caused by mutations in the BICD2 gene, which encodes the Bicaudal D2 protein. This protein plays a crucial role in the microtubule dynamics essential for neuronal function and survival. The mutations lead to a disruption in the transport of cellular components, affecting the health and maintenance of motor neurons. As a result, individuals with SMA-LED2A experience progressive muscle weakness and atrophy, primarily in the lower extremities.

Symptoms and Diagnosis

The onset of symptoms in SMA-LED2A can vary but typically begins in childhood or adolescence. The primary symptom is progressive muscle weakness, starting in the legs and potentially affecting the upper limbs in later stages. Other symptoms may include difficulty walking, frequent falls, and muscle contractures.

Diagnosis of SMA-LED2A involves a combination of clinical examination, family history, genetic testing to identify mutations in the BICD2 gene, and sometimes electromyography (EMG) to assess muscle and nerve function. Genetic counseling is recommended for affected individuals and their families to understand the inheritance pattern and implications of the disorder.

Treatment and Management

There is currently no cure for SMA-LED2A, and treatment focuses on managing symptoms and improving quality of life. Physical therapy and rehabilitation exercises are crucial to maintain mobility and prevent contractures. Orthopedic interventions may be necessary for some individuals to address skeletal deformities and mobility issues. Regular follow-up with a multidisciplinary team of healthcare providers, including neurologists, orthopedists, and physical therapists, is essential for optimal management of the condition.

Prognosis

The prognosis for individuals with SMA-LED2A varies. While the disorder is progressive, the rate of progression can differ significantly among affected individuals. Some may maintain functional mobility into adulthood, while others may experience increased weakness and mobility challenges. Early intervention and supportive care can help manage symptoms and improve the quality of life.

See Also

• Spinal muscular atrophy
• Genetic disorder
• Muscle weakness
• Autosomal dominant inheritance

NIH genetic and rare disease info

• NIH info on Spinal muscular atrophy with lower extremity predominance 2A

Spinal muscular atrophy with lower extremity predominance 2A is a rare disease.