SEPN1

The SEPN1 gene provides instructions for making a protein called selenoprotein N. This protein is part of a family of selenoproteins, which have several critical functions within cells. Selenoproteins are involved in chemical reactions called oxidation-reduction reactions, which are essential for storing and releasing energy. Proteins in this family also help process hormones produced by the thyroid (a butterfly-shaped gland at the base of the neck).

The exact function of selenoprotein N is unknown. This protein is highly active in many tissues before birth and may be involved in the formation of muscle tissue (myogenesis). Selenoprotein N may also be important for normal muscle function after birth, although it is active at much lower levels in adult tissues. The protein contains a region that likely allows it to bind to calcium. This region is of interest because calcium plays an important role in triggering muscle contractions, which allow the body to move.

multiminicore disease - caused by mutations in the SEPN1 gene

More than 10 mutations in the SEPN1 gene have been identified in people with the classic form of multiminicore disease. Most of these genetic changes lead to the production of an abnormally short version of selenoprotein N. Other mutations change single protein building blocks (amino acids) in critical regions of the protein. The effects of changes in the structure and function of selenoprotein N are unknown, and researchers are working to determine how these changes lead to muscle weakness and the other characteristic features of multiminicore disease.

other disorders - caused by mutations in the SEPN1 gene

Mutations in the SEPN1 gene are responsible for several rare muscle disorders whose characteristic features overlap with those of multiminicore disease. These conditions include rigid spine muscular dystrophy, congenital fiber-type disproportion, and desmin-related myopathy with Mallory body-like inclusions.

All of these related conditions cause muscle weakness, particularly in the muscles of the trunk and neck. Affected individuals also have weak muscle tone (hypotonia), abnormal curvature of the spine (scoliosis), and serious problems with breathing. Because they have a similar pattern of signs and symptoms and are caused by mutations in the same gene, many researchers believe that these conditions are all part of a single syndrome with variable signs and symptoms. Together, muscle diseases caused by SEPN1 mutations are known as SEPN1-related myopathy.