Congenital muscular dystrophies: 1997 update.

The congenital muscular dystrophies (CMDs) comprise a heterogeneous group of muscle disorders with onset in utero or during the first year of life. Several forms of CMD show various types of brain involvement in addition to a muscular dystrophy. Two forms are defined at the molecular level: merosin deficient-CMD caused by mutations in the LAMA2-gene on chromosome 6q2. Fukuyama congenital muscular dystrophy (FCMD) is prevalent in Japan and caused by an as yet unidentified gene on chromosome 9q31. At least two further forms of CMD with brain involvement are nosologically well defined: Walker--Warburg-CMD is characterized by lissencephaly type 11, eye dysgenesis and muscular dystrophy. This autosomal recessive disorder is fatal or results in complete lack of development. A similar but much milder phenotype with pachygyria of the brain, various degrees of eye changes and milder muscular dystrophy that is compatible with achievement of simple motor milestones has been described under the name of muscle-eye-brain disease (MEB) in Finland. A number of nosologically less distinct forms of muscular dystrophy have been outlined such as 'pure' CMD without brain involvement, CMD with cerebellar hypoplasia or CMD type Ullrich with hyperelasticity of the distal joints. Several other CMD phenotypes are known, some of which are suggestive of more distinctly separate nosological entities due to their occurrence in siblings or due to a characteristic pattern of clinical, histopathological and imaging features, and await further clarification.