SEPN1-related myopathy (including subtypes, previously referred to as rigid spine congenital muscular dystrophy or RSMD1 and minicore myopathy) is caused by changes in the gene SEPN1, which is responsible for the production of a protein called selenoprotein N (SEPN1).
SEPN1-related myopathy, a subtype of congenital muscular dystrophy, has specific features, including:
- the spine is ‘rigid’ or ‘stiff’ and can have an S-shaped curvature (scoliosis)
- muscle weakness is relatively mild compared to other forms of congenital muscular dystrophy and mainly involves the ‘axial’ muscles (muscles of the neck and trunk) and, to a lesser extent, the limbs
- respiratory insufficiency develops before adulthood with the need for night-time noninvasive ventilation typically evident while individuals remain ambulant.
The condition is fairly stable. People who have SEPN1-related myopathy appear, at least initially, to gain strength as they age. However, while motor function remains relatively
stable, with only slowly progressive muscle weakness, the curvature of the spine (scoliosis) can progress rapidly. For this reason, it is important to monitor carefully the progression of the curvature of the spine in SEPN1-related myopathy and refer to a specialist spinal clinic as needed.