We studied centromeric SMN gene deletions in various forms of congenital muscular dystrophies. Our study cohort consisted of 48 patients (43 families): 24 with merosin-positive CMD, 18 with merosin-deficient CMD and 6 with muscle-eye-brain (MEB) disease. None of the patients showed deletions of the telomeric gene; however, the deletion frequency of the centromeric gene was 27%. In a multiplex family, the mildly affected sibling, who is ambulant, had a preserved centromeric copy of the SMN gene, whereas in the severely affected sibling the copy was missing. The centromeric copy of the SMN gene may have a contributing role in the phenotype of patients with CMD, as well as other modifying genes or environmental factors.

We studied centromeric SMN gene deletions in various forms of congenital muscular dystrophies. Our study cohort consisted of 48 patients (43 families): 24 with merosin-positive CMD, 18 with merosin-deficient CMD and 6 with muscle-eye-brain (MEB) disease. None of the patients showed deletions of the telomeric gene; however, the deletion frequency of the centromeric gene was 27%. In a multiplex family, the mildly affected sibling, who is ambulant, had a preserved centromeric copy of the SMN gene, whereas in the severely affected sibling the copy was missing. The centromeric copy of the SMN gene may have a contributing role in the phenotype of patients with CMD, as well as other modifying genes or environmental factors.