SEVERE CLASSICAL CONGENITAL MUSCULAR-DYSTROPHY AND MEROSIN EXPRESSION

It has been suggested that patients with autosomal recessive merosin d eficient congenital muscular dystrophy (CMD), as opposed to the merosi n positive cases form a homogeneous subgroup of a clinically mole seve re form of CMD. We examined merosin expression in muscle biopsies from five children with the severe classical form of CMD. Merosin deficien cy was found only in 1 patient, a 6-year-old female, with abnormal bra in myelination. However, her initial biopsy did not reveal the classic al picture of dystrophy. The four merosin positive cases exhibited sev ere muscle weakness but their brain imagings were normal. There were n o familial cases, except for the mother of 1 patient who had a milder form of the disease, suggesting an autosomal dominant mode of inherita nce. In contrast to previous reports, the merosin deficient CMD cases were rare in our group. Furthermore, merosin positive cases were also associated with severe phenotype suggesting that a severe phenotype is not exclusive to merosin deficient cases. Finally, the absence of mer osin in a neonate with hypotonia and weakness can be helpful in making a definitive diagnosis of CMD, even though the dystrophic process may not be evident yet and histology may be non-specific.