Sarcoglycanopathies: An enigmatic form of muscular dystrophy - A report of 7 cases

BACKGROUND: Limb girdle muscular dystrophy (LGMD) is a phenotypic expression of a heterogeneous group of diseases and sarcoglycanopathy is one of the causes of LGMD. There is only one study on sarcoglycanopathies in the Indian literature. No data is available from northern India.
MATERIALS AND METHODS: All cases of muscular dystrophies, which were diagnosed in our laboratory in the last six years, were reviewed. Immunohistochemistry for various sarcoglycan proteins was done. Clinical features and pathological findings of the cases that were diagnosed as sarcoglycanopathies were reviewed.
RESULTS: In the last 6 ½ years (1998-June 2004), we received 1435 muscle biopsies, of which 498 cases were of muscular dystrophies, and 13 cases were of sarcoglycanopathies (8 of gamma, 3 of alpha, 1 of both alpha and gamma, and 1 with absence of all four sarcoglycans). Sarcoglycanopathies comprised 2.6% of all muscular dystrophies, 11.8% of LGMD and 0.90% of all muscle diseases diagnosed in our laboratory. The mean age of onset was 7.2 years and the M:F ratio was 1.1:1. Most of them presented with difficulty in getting up, climbing stairs, calf hypertrophy and markedly raised CPK levels. Histological features were like dystrophinopathies.
CONCLUSION: Sarcoglycanopathies are a relatively rare cause of LGMD and should be confirmed by immunohistochemistry as it will facilitate counseling and also prognostification. Although rare, in patients with muscle weakness, calves hypertrophy and raised CPK levels this possibility should be considered and needs to be differentiated from dystrophinopathies.

Keywords
Muscular dystrophy, sarcoglycanopathy, SCARMD, LGMD, histochemistry, muscle immunohistochemistry