Spectrum of congenital myopathies: a single centre experience

Abstract

Background: Congenital myopathies (CMs) are rare and they are clinically and genetically heterogeneous. Muscle biopsy is characterized by structural abnormality that is diagnostic. There are few studies from India.

Materials and methods: This is a retrospective study of 12 years. The demographic data, clinical features and laboratory data of patients diagnosed as CMs on muscle biopsy were retrieved from medical records. The slides were reviewed for morphological and structural abnormalities using the following stains hematoxylin and eosin, modified Gomori trichrome, masson trichrome, periodic acid schiff, adenosine triphosphatase preincubated at pH 9.4, 4.6 and 4.3, nicotinamide adenine dinucleotide tetrazolium reductase, succinic dehydrogenase and cytochrome c oxidase. Immunohistochemistry was performed with dystrophin, sarcoglycans and desmin wherever necessary.

Results: There were 50 patients with CMs: Centronuclear myopathy (23), myotubular myopathy (3) and central core disease (CCD) (8), nemaline myopathy (5), congenital fiber type proportion (10) and desmin related myopathy with arrythmogenic right ventricular cardiomyopathy (ARVD) (1). Of the 50 patients, 30 (60%) presented in the first decade of life. Proximal muscle weakness and hypotonia were the common presenting features. Type 1 atrophy and predominance were seen in most cases on muscle biopsy. CCD had one patient with high creatine phosphokinase levels, biopsy in one patient showed both rods and cores, in the other limb girdle muscular dystrophy like picture and one biopsy showed uniform type 1 fibers. There was one desmin related myopathy with ARVD, who had cardiac transplantation and both skeletal and cardiac muscle showed characteristic rimmed vacuoles and inclusions positive for desmin.

Conclusion: CMs are rare and the diagnosis can only be established on muscle biopsy. Defining the specific CMs helps the clinician in counseling the patient and family.