Background: Miyoshi myopathy (MM) and limb girdle muscular dystrophy (LGMD2B) are distinct clinical entities because different muscle groups are involved at the onset. We describe the clinical features in 28 patients with dysferlin deficiency confirmed by muscle immunohistochemistry (IHC).
Settings and design: A case series from a tertiary national referral center for neurological disorders.
Materials and methods: Patients with classical phenotype of MM and LGMD2B underwent a thorough phenotypic characterization followed by muscle histopathological study including IHC for dysferlin deficiency.
Results: There were 28 patients (20 men and eight women) presenting with manifestations of distal myopathy or LGMD2B and had absence of dysferlin staining on IHC. Patients presented predominantly with distal myopathy of Miyoshi type (MM) or proximal LGMD type and were diagnosed to have dysferlinopathy on IHC. Two patients had the proximodistal form and two had onset as tibial muscular dystrophy. The main clinical features in these patients were onset in late adolescence or early adulthood (mean age of onset for MM was 22.0 +/- 6.7 years and for LGMD2B 19.4 +/- 5.1 years). There was early and predominant involvement of the posterior compartment muscles of the leg or proximal pelvic girdle muscles, dystrophic features with necrotic regeneration pattern without vacuoles on muscle biopsy and markedly elevated serum creatine kinase values with mean of 10033.8 +/- 9283 IU/l (range 402-27460). Consanguinity was reported in 46.4%. The mean duration of illness was 6.4 +/- 4.2 years. Dysferlinopathies formed nearly one-fourth of our patients with LGMD.
Conclusion: In our experience dysferlinopathies was not an uncommon form of LGMD.