Congenital Muscular Dystrophies (CMDs) are extremely rare neuromuscular disorders with onset at birth or early infancy, characterized by muscle weakness (hypotonia), delayed motor development; difficulties in walking, breathing or feeding, joint retractions or stiffness. They are very heterogeneous, so that patients may present with symptoms of varying severity.

There are currently almost thirty known genes responsible for CMDs.

• The five main forms of DMC are:

  • 1• Merosinopathies including merosin-negative CMD (MDC1A), due to mutations in the LAMA2 gene, which encodes the α2 chain of the laminin (or merosin) protein. 

  • 2• Collagenopathies related to collagen type VI including Ullrich-type CMD (UCMD), Bethlem Myopathy and other myopathies caused by mutations in one of the 3 collagen VI genes (COL6A1, COL6A2 and COL6A3).

  • 3• Dystroglycanopathies, caused by a disorder of alpha-dystroglycan glycosylation, with syndromic forms including mental retardation or structural brain abnormalities (Fukuyama type, Muscle-Eye-Brain type, Walker-Warburg type) and others without mental retardation.

  • 4• Selenoproteinopathies or rigid spine syndrome type 1 (RSMD1), due to mutation of the selenoprotein N1 gene (SEPN1).

  • 5• Congenital laminopathies (L-CMD), linked to the lamin A/C gene (LMNA).