Objectives: To determine the prevalence of merosin deficiency in cases of unclassified congenital muscular dystrophy and to determine the temporal stability of merosin epitopes in fixed and stored archival material.
Materials and methods: Using an antibody to human merosin we retrospectively studied 12 cases of undiagnosed muscular dystrophy from our files to determine the prevalence of merosin deficiency. Where fresh muscle was not available, unstained stored cryostat sections or destained archival stored sections were incubated with the merosin antibody.
Results: Two of the 12 cases of undiagnosed muscular dystrophy were merosin-deficient. No difference in intensity of merosin staining was found between freshly cut cryostat sections and unstained stored cryostat sections. There was no difference in the intensity of merosin staining in sections archived for up to 10 years.
Conclusions: We conclude that 16% of unclassified muscular dystrophies in our study are due to merosin deficiency and that merosin antigenicity remains intact in archival stored muscle tissue, facilitating retrospective evaluation of patients in whom frozen muscle is not available. To our knowledge, this latter observation has not been reported previously.