congenital myopathy SELENON-related myopathy SELENON-related myopathy Myopathy caused by pathogenic variants in SELENON that is congenital or present early in childhood with neonatal hypotonia, delayed motor development, axial muscle weakness, scoliosis, and significant respiratory involvement. Spinal rigidity of varying severity is often present. SEPN1-related myopathy MONDO:0100100 GARD:0026047