G71.21

Clinical Causes: Genetic mutations are the primary cause of nemaline myopathy, often inherited in an autosomal dominant or recessive pattern. Mutations affect genes responsible for producing proteins essential to muscle fiber structure, such as ACTA1, NEB, and TPM3. In some cases, the exact genetic cause remains unknown, and the disorder may result from de novo mutations. Environmental factors do not play a role in the development of this genetic condition.

Key Symptoms: Muscle weakness that is often more noticeable in proximal muscles such as shoulders, hips, and neck. Delayed motor development in infants, including difficulties sitting, crawling, or walking. Poor muscle tone (hypotonia), leading to floppy infants. Feeding difficulties in infants due to weak facial and oropharyngeal muscles. Respiratory issues, including breathing difficulties caused by weakened respiratory muscles. Facial muscle weakness, which can cause a characteristic facial appearance with poor expressions. Signature slow or clumsy movements, sometimes described as a 'floppy' or 'swaying' gait.

Diagnosis Path: Diagnosis typically involves a combination of clinical examination, family history, and specialized tests. Muscle biopsy reveals the characteristic nemaline bodies, which are rod-like structures within muscle fibers, identifiable under microscopy. Genetic testing can identify mutations in genes associated with the disorder. Electromyography (EMG) may be used to assess muscle electrical activity, and other imaging or clinical assessments help evaluate the extent of muscle weakness. Early diagnosis is important for management and planning supportive therapies.

Treatment Protocols: There is currently no cure for nemaline myopathy. Management focuses on alleviating symptoms and improving muscle strength. Common approaches include: - Physical therapy to maintain muscle strength and mobility. - Occupational therapy to assist with daily activities. - Respiratory support, including breathing exercises or ventilatory assistance if necessary. - Nutritional support, especially in infants with feeding difficulties. - Regular monitoring for respiratory and cardiac function. - Assistive devices such as braces, wheelchairs, or other mobility aids to enhance independence. Emerging therapies and clinical trials are continually being explored to better understand and treat this condition in the future.