Diagnostic Pitfalls of an Atypical Form of Congenital Muscular Dystrophy - Partial Merosin Deficiency - Case Reports
Abstract
Congenital muscular dystrophies are a group of inherited muscle disorders characterized. by early onset of muscle weakness and dystrophic changes in muscle biopsy. Mutation of the laminin; gene resulting in total or partial merosin deficiency is the most common cause in European population.
Total loss of merosin manifests as congenital muscular dystrophy type 1A, partial deficiency results in limb girdle weakness of variable severity. Diagnosis of partial deficiency is based on clinical manifestation, brain magnetic resonance imaging (MRI) with apparent leucodystrophy, electromyography with documented peripheral neuropathy and genetic examination, muscle MRI pattern of pathological changes may be beneficial in differential diagnosis.
Muscle biopsy shows dystrofic changes but immunohistochemistry may not reveal merosin deficiency and so it can be misleading. Treatment is symptomatic, correct diagnosis can help in predicting the course of the disease and associated risks and facilitates genetic counselling.
It is likely that, due to the difficult diagnosis, partial merosin deficiency occurs more frequently than currently estimated. The authors present three illustrative case reports.