Sarcoglycan deficiency in a large Italian population of myopathic patients.

Autosomal recessive limb-girdle muscular dystrophies are a heterogeneous group of genetic diseases with a wide spectrum of clinical severity and age of onset; mutations in the gene encoding the dystrophin-associated sarcoglycan proteins (alpha, beta, gamma and delta) have recently been shown to cause some cases of these myopathies (primary sarcoglycanopathies, types 2D, 2E, 2C and 2F, respectively). In this study we have examined a large population of Italian myopathic patients to determine the frequency of (alpha-, beta- and gamma-sarcoglycan deficiency and to correlate molecular defects with clinical phenotypes; to exclude the presence of primary dystrophinopathies both genetic and immunological analysis of dystrophin was performed. We report 12 patients (10 male and 2 female) with deficiency of either one or more sarcoglycan proteins. They were aged 8-56 years with onset between 4 and 30 years of age; they all presented with either mild, moderate or severe limb-girdle involvement associated with elevated blood creatine kinase levels and myopathic pattern at EMG; one was also affected with a mild dilation cardiomyopathy. All patients, except one, showed pathological muscle histological changes. Absence of all three proteins always correlates with severe forms, whereas mild protein deficiencies or isolated partial alpha-sarcoglycan deficiency correlate with either severe, moderate or mild forms.

Asymptomatic familial hyperCKemia associated with desmin accumulation in skeletal muscle.

We describe a family, two brothers and their mother, who came to our observation because of slight to moderate hyperCKemia. The younger brother, who had the highest CK values, was only suffering from episodic myalgia, the other two members of the family were asymptomatic. Neurological examination was normal. Both brothers underwent muscle biopsy which was significant for the presence of abnormal sarcoplasmic areas of desmin accumulation. So far, desmin abnormalities have never been reported in patients with such a mild neuromuscular pattern. We discuss possible correlations between severity of clinical phenotype and degree of desmin accumulation.

Utrophin expression during human fetal development.

Utrophin, a protein encoded by chromosome 6 is highly homologous to the cysteine-rich domain and most of the C-terminal domain of dystrophin. In order to clarify its functional role we analyzed its expression during human fetal development. We carried out immunohistochemical analysis on muscle from normal human fetuses at different ages of gestation using an antibody directed against a specific COOH-terminal sequence of the protein. In addition, we stained serial sections with antibodies against dystrophin and alpha-bungarotoxin FITC-BTX. Our findings show that, at week 9 of gestation, utrophin is diffusely expressed in the cytoplasm. From week 12 to 22 the immunostaining is still cytoplasmic, though the reaction intensity progressively decreases. Moreover we observed a strong reaction in fetal nerve at week 18 and 22. There was no correlation between utrophin expression and progressive dystrophin membrane localization.

High serum creatine kinase levels associated with cylindrical spirals at muscle biopsy.

We studied the muscle biopsy from an asymptomatic patient with high serum creatine kinase values. Subsarcolemmal and intermyofibrillar granular inclusions were seen at the light microscopy level. Ultrastructural observation showed clusters of cylindrical spirals (CS). CS are nonspecific, morphological finding, so far reported only in a few cases, presenting with a wide variety of clinical phenotypes. The case we describe is peculiar because of the complete lack of clinical symptoms. The nature of the CS is unknown; we studied a possible alteration of cytoskeletal proteins using a set of different antibodies against these structures, but none of them reacted with CS. Also, since CS have been described in association with mitochondrial abnormalities, and since in our case CS were strongly positive when stained for succinate dehydrogenase, we performed specific immunohistochemical and genetic studies which ruled out any major mitochondrial alterations.