Myopathy accumulation of actin (Actin-accumulation myopathy) - Gen ACTA1.

Myopathy actin accumulation is a disorder that primarily affects skeletal muscles, causing myopathy and hypotonia in the body.

Signs and symptoms of this disease are evident in childhood and include feeding difficulties swallowing, weak cry and difficulty in controlling the movements of the head. Myopathy also affects the respiratory muscles, causing shallow breathing, leading to a decrease in oxygen and an accumulation of carbon dioxide in the blood, which can cause frequent respiratory infections and potentially fatal respiratory problems. Because respiratory problems, individuals most affected do not survive beyond infancy.

This disease is due to mutations in the gene ACTA1, located on the long arm of chromosome 1 (1q42.13). This gene encodes actin skeleton protein alpha (?), which is a member of the family of proteins actin found in skeletal muscles. Actin proteins are important for cell movement and muscle contraction. Thin filaments consist of actin molecules and thick filaments compounds of another protein called myosin are the primary components of muscle fibers that are important for muscle contraction.

They have been identified at least 9 ACTA1 gene mutations, causing accumulation of actin myopathy. Most of these mutations change the amino acid sequence of the protein ? - skeletal actin. It is believed that genetic mutations can affect the way that actin binds the ATP molecule. This molecule supplies energy for cell activities and is important in the formation of fine filaments from individual actin molecules. Dysfunctional -ATP actin binding may result in abnormal formation of fine filament and alters muscle contraction, which causes muscle weakness and other signs and symptoms of the disease. In some people, they have not identified mutations in the gene ACTA1. The cause of the disease in these individuals is unknown.

This disease is inherited as an autosomal dominant, which means that a copy of the altered gene in each cell is sufficient to cause the alteration. Most cases are not inherited, the result of new mutations in the gene and occur in people with no history of disease in your family.  

Tests in IVAMI: in IVAMI perform detection of mutations associated with myopathy actin accumulation by the complete PCR amplification of exons ACTA1 gene, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).