Congenital
muscular dystrophy type 1A (MDC1A) is an autosomal recessive disorder characterized by
hypotonia, elevated serum
creatine kinase level, delayed motor milestones, white matter changes observed by brain magnetic resonance imaging, and normal intelligence. A mutation in the
laminin α2 (LAMA2) gene, located at 6q22-23, is a genetic cause of MDC1A. Patients have
merosin (laminin α2)-deficient skeletal muscles. However, the degree of
merosin expression ranges from total absence to partial reduction. Patients with residual
merosin expression have more variable and milder phenotypes than those with absolute
merosin deficiency. We observed a Korean girl with MDC1A with residual
merosin expression. Clinical presentation of this patient was typical except for late onset of the disease and external capsule involvement. Immunohistochemical staining of muscle fibers including
merosin, is important to evaluate patients with
hypotonia, delayed motor development, and abnormal white matter changes.