Muscle pathology in 31 patients with calpain 3 gene mutations..

BACKGROUND AND PURPOSE: At present, more than 20 different forms of limb-girdle muscular dystrophies (LGMDs) are known (at least 7 autosomal dominant and 14 autosomal recessive). Although these different forms show some typical phenotypic characteristics, the existing clinical overlap makes their differential diagnosis difficult. Limb-girdle muscular dystrophy type 2 (LGMD2A) is the most prevalent LGMD in many European as well as Brazilian communities and is caused by mutations in the gene CAPN3. Laboratory testing, such as calpain immunohistochemistry and Western-blot analysis, is not totally reliable, since up to 20% of molecularly confirmed LGMD2A show normal content of calpain 3 and a third of LGMD2A biopsies have normal calpain 3 proteo-lytic activity in the muscle. Thus, genetic testing is considered as the only reliable diagnostic criterion in LGMD2A. MATERIAL AND METHODS: In an attempt to find a correlation between genotype and muscle pathology in limb-girdle muscular dystrophy 2A we performed histopathological investigation of a group of 31 patients subdivided according to the type of pathologic CAPN3 gene mutation. RESULTS: In all biopsies typical features of muscular dystrophy such as fiber necrosis and regeneration, variation in fiber size and fibrosis were noted. Lobulated fibers were often encountered in the muscle biopsies of LGMD2A patients. Such fibers were more frequent in patients with 550delA mutation. CONCLUSIONS: These findings may be helpful in establishing diagnostic strategies in LGMD.

Evidence for autoimmunity to heart-specific antigens in patients with Emery-Dreifuss muscular dystrophy.

Dilated cardiomyopathy is one of the leading abnormalities in Emery-Dreifuss Muscular Dystrophy (EDMD). The pathogenesis of heart involvement in EDMD is, however, unknown. Autoimmune mechanisms have also to be taken into account. The aim of this study was to search for the presence of anti-heart antibodies in EDMD patients. The anti-heart auto-antibodies were detected in serum of 14 EDMD patients (the X-linked and the AD-Autosomal Dominant form). The control groups comprised 10 patients with Dilated Cardiomyopathy (DCM) and 10 healthy subjects. To screen serum for anti-heart antibodies against ventricular muscle proteins, they were separated by polyacrylamide gel electrophoresis, followed by Western blotting. In EDMD and DCM, IgG anti-heart antibodies against heart ventricular proteins were detected. In both diseases, 85 kD protein appeared to be the most immunogenic. Anti-troponin I (24 kD), anti-tropomyosin (35 kD) and anti-actin (43 kD) reactivity was less intense. There were significant differences in the reactivity of auto-antibodies between both EDMD forms, and also between EDMD and the DCM patients. No clear-cut correlation between the reactivity and frequency of the antibodies and clinical parameters of the EDMD patients was detected. The anti-heart proteins are reliable markers of immune involvement in dilated cardiomyopathy in the course of EDMD. Short- and long-term follow-up may define the role of anti-heart antibodies in predicting the susceptibility at risk of dilated cardiomyopathy in EDMD patients.

Atypical motor unit potentials in Emery-Dreifuss muscular dystrophy (EDMD).

OBJECTIVE: The aim of the study was to analyse electromyographic changes in Emery-Dreifuss muscular dystrophy (EDMD) that are atypical for myopathy. Our special interest was focused on high amplitude polyphasic motor unit potentials (MUPs), also termed irregular MUPs. METHODS: We studied 21 EDMD patients with the diagnosis based on clinical data, DNA analysis and immunohistochemical muscle studies. Rectus femoris muscle biopsies were investigated in all affected patients. Electrophysiological investigations involved quantitative concentric needle electromyography (CNEMG) of biceps brachii (BB) and rectus femoris (RF) muscles. Simulation studies were performed to approximate the number, diameter and distribution of muscle fibers, which contribute to irregular MUPs. RESULTS: The EMG data in EDMD were compatible with myopathy. Irregular MUPs showed longer duration, larger area, size index and higher amplitude then simple ones (P < 0.05). The approximation of features of muscle fibers contributing to irregular MUP also indicated smaller (<45 microm) and larger (>55 microm) diameters than normal (50 +/- 5 microm). Muscle biopsy specimens revealed the variable muscle fiber size due to atrophy, hypertrophy, and muscle fiber splitting. CONCLUSIONS: Irregular MUPs recorded in EDMD are due to hypertrophied and atrophied fibers as well as increased fiber density. They reflect reorganization of the motor unit in a slow progression myopathic process (muscle fiber hypertrophy and splitting). SIGNIFICANCE: Irregular MUPs in EDMD most probably reflect increased variability of the muscle fiber size.

Dystrophinopathies in females.

Various laboratory tests were performed to establish carriership in 24 familial and sporadic carriers of Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD). The activity of creatine kinase was in all females but one, very high and significantly higher in isolated carriers; quantitative EMG indicated myopathic changes, muscle biopsies revealed different degrees of changes--from a variability of muscle fibers size and central nuclei to severe dystrophic features. Immunohistochemical evaluation of dystrophin revealed, in all females but one, mosaic pattern of staining--a mixture of dystrophin-positive and dystrophin-negative fibers, the latter consist 15-30% of all fibers. Quantitative evaluation of dystrophin showed a reduced abundance with normal or abnormal molecular weight. The abnormalities were more expressed in sporadic cases. The detection of sporadic carriers, particularly the non-manifesting clinical, is a very important progress--it permits the correct diagnosis (before, these females were diagnosed as limb girdle muscle dystrophy (LGMD) and supply them with the benefit of genetic counselling, which also requires some modification.

[Hereditary neuropathy with liability to pressure palsies caused by 17p11.2 chromosome deletion]. / Dziedziczna neuropatia z nadwrazliwoscia nerwów na ucisk spowodowana delecja w chromosomie 17p11.2.

Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominant disorder characterised by recurrent mononeuropathies. Electrophysiological studies reveal slowed conduction velocity in peripheral nerves. The main histopathological findings are focal thickenings of myelin-tomaculae. In most cases HNPP is associated with a deletion within PMP-22 (peripheral myelin protein; PMP) gene on chromosome 17p11.2. The gene penetration is almost complete but the expression may be variable. DNA analysis is of practical importance in diagnosing HNPP especially in sporadic cases and also in individuals without clinical and electrophysiological signs of neuropathy. We present the first Polish family with HNPP, in which the genetic defect has been confirmed by DNA analysis.

[Muscular dystrophies with dystrophin glycoprotein complex deficit]. / Dystrofie miesniowe z deficytem komponentów glikoproteinowego kompleksu dystrofiny.

Progressive muscular dystrophies with primary or secondary dystrophin glycoprotein complex components' deficit are described. Some variants of limb--girdle and congenital muscular dystrophies as well as Duchenne/Becker muscular dystrophy belong to this group. The structure of dystrophin glycoprotein complex (DGC) which is localised within muscle sarcolemma is presented. Usefulness of the assessment of the particular DGC components is underlined and importance of the resulting prognostic as well as diagnostic implications are stressed.