Monarch Disease Ontology identifier MONDO_0011271 (rigid spine muscular dystrophy 1) is an inherited muscular dystrophy caused by mutations in the SEPN1 gene. It is characterized by severe limitation in flexion of the dorsolumbar and cervical spine, due to contracture of the spinal extensors. It leads to loss of movement of the spine and the thoracic cage. Also known as: Eichsfeld type congenital muscular dystrophy, MDRS1, RSMD1, RSS, SELENON rigid spine syndrome, congenital merosin-positive muscular dystrophy with early spine rigidity, desmin-related myopathy with Mallory bodies, minicore myopathy, severe classic form.