The selenoprotein N (SEPN1) gene on chromosome 1p36 was considered as a candidate for MmD because of the considerable clinical and histopathologic overlap between the classic phenotype of MmD (see paragraph above on clinical description) and congenital muscular dystrophy with rigidity of the spine (RSMD) due to SEPN1 mutations [39]; both conditions share a similar phenotype with marked axial weakness, spinal rigidity, early scoliosis and respiratory impairment, and histopathologic features of RSMD may be rather more myopathic than dystrophic, with typically a normal creatine kinase (CK). This evidence concerns the gene SELENON and congenital muscular dystrophy.