Transforming growth factor-beta1 and fibrosis in congenital muscular dystrophies

We evaluated transforming growth factor-beta1 (TGF-beta1) expression in the muscle of four laminin alpha2-negative, four laminin alpha2-positive and seven partial laminin alpha2-deficient congenital muscular dystrophy (CMD) patients, and compared it to Duchenne muscular dystrophy (DMD) patients and controls. TGF-beta1 mRNA levels in skeletal muscle from laminin alpha2-negative and laminin alpha2-positive CMD patients were significantly greater than in controls (P < 0.05 and P < 0.005, respectively), while in partial laminin alpha2-deficient muscular dystrophy patients the amount was not significantly higher than in controls (P > 0.1). The TGF-beta1 values were lower than those found in DMD, although the extent of fibrosis was greater in CMD than in DMD and controls. Our findings suggest that TGF-beta1 is involved in CMD muscle fibrosis, but differently from what we observed in DMD muscles as it seems not to be the major player in connective tissue proliferation.

Congenital muscular dystrophy with merosin deficiency: MRI findings in five patients

We present the MRI findings in five patients with congenital muscular dystrophy (CMD) and merosin (laminin alpha2) deficiency, which was total in one and partial in four. In one patient with partial merosin deficiency, MRI was normal. The other four patients had supratentorial white matter abnormalities. In three, T2-weighted images revealed subcortical, deep lobar and periventricular high signal in white matter, while in the other there were only small peritrigonal areas of increased signal. On T1-weighted images, there was slightly low signal. Cortical abnormalities were absent. None of these changes were accompanied by symptoms or signs of central nervous system involvement. White matter abnormalities in a patient with CMD should prompt investigation of merosin.

A new non-radioactive method for the screening and prenatal diagnosis of myotonic dystrophy patients

Myotonic dystrophy (DM) is an autosomal dominant neuromuscular disease with an estimated incidence of 1 in 8000 and is the most common form of muscular dystrophy affecting adults. An unstable, untranslated part of the myotonic dystrophy protein kinase gene on the long arm of chromosome 19, composed of CTG repeats, is a genetic marker for DM. We have developed a fast non-radioactive polymerase chain reaction (PCR) procedure to detect the (CTG)n repeat expansion in DM patients and their relatives. Genomic DNA extracted from peripheral blood lymphocytes was amplified by PCR using specific primers to flank the region containing the triplets. To improve the amplification of this CG-rich region, either 10% glycerol or rTth DNA polymerase XL (extra long) was added to the reaction mixture, allowing amplification of huge expansions otherwise not polymerized by PCR. The PCR products were Southern blotted and the expansion revealed using a fluorescein-labelled (CTG)10 probe. We compared our results with those obtained in 24 patients and relatives using genomic digestion followed by radioactive Southern blot; in all cases the results overlapped. The same technique was used for prenatal diagnosis in pregnant DM mothers. We conclude that this new method is reliable for the genetic testing of DM patients.

X-linked Emery-Dreifuss muscular dystrophy can be diagnosed from skin biopsy or blood sample

We have raised an anti-emerin polyclonal antibody against a fusion protein encompassing most of the hydrophilic portion of emerin. Using this antibody, we have analyzed emerin expression in Emery-Dreifuss muscular dystrophy (EDMD) patients and controls, by immunocytochemistry, in skeletal muscle and skin, and by immunoblot, in peripheral blood mononuclear cells and lymphoblasts. Emerin was localized on the surfaces of nuclei in control skeletal muscle and skin but was absent or reduced in patient skeletal muscle, was absent from the skin of patients, and was expressed only in a few nuclei in a patient's mother. Immunoblot of peripheral blood cells from EDMD patients showed absence of the emerin band, altered-size emerin, or a protein of normal molecular mass but slightly reduced quantity. The diagnosis of X-linked EDMD is normally confirmed by genetic analysis of the STA gene coding for emerin. We propose immunocytochemical evaluation of emerin expression in skin biopsies as a sensitive and more convenient tool for diagnosing X-linked EDMD and, in particular, for distinguishing it from the autosomal dominant form. This technique may be applied to suspected EDMD patients, especially sporadic cases or those with incomplete clinical phenotype, and also suspected carriers. Immunoblot of peripheral blood cells is also useful, but it may not unequivocally identify carriers and some patients.

Concomitant deficiency of beta- and gamma-sarcoglycans in 20 alpha-sarcoglycan (adhalin)-deficient patients: immunohistochemical analysis and clinical aspects

We have investigated the expression, using immunohistochemistry, of beta- and gamma-sarcoglycans in the muscles of 20 patients in whom previous screening had revealed a deficiency of alpha-sarcoglycan. alpha-, beta- and gamma-sarcoglycans were absent in 7 patients and variably reduced in 8 patients, in 2 of whom beta-sarcoglycan was more reduced than the alpha- and gamma-proteins. In 5 other patients with variably reduced alpha- and beta-sarcoglycans, gamma-sarcoglycan was completely absent. In all patients the distribution of hyposthenia at disease onset was similar, and predominantly involved pelvic girdle muscles; however, the age at onset and rate of disease progression were highly variable. In severely compromised patients, the onset of disease was before 10 years of age and gamma-sarcoglycan or all three sarcoglycans were absent from muscles. Immunohistochemical analysis of sarcoglycans should be part of routine screening for muscle dystrophies to identify patients with sarcoglycanopathy. Gene analysis is necessary to identify the primary defect; however, sarcoglycan immunohistochemistry may be useful for indicating which gene to investigate. Further biochemical characterization of the interactions between these proteins is required to fully elucidate their roles in causing severe, moderate or mild muscular dystrophy.

Dystrophin-associated protein abnormalities in dystrophin-deficient muscle fibers from symptomatic and asymptomatic Duchenne/Becker muscular dystrophy carriers

The absence of dystrophin in muscle fibers is associated with a major reduction in dystrophin-associated proteins (DAPs) and disruption of the linkage between the subsarcolemmal cytoskeleton and the extracellular matrix. We investigated the expression of the DAPs beta-dystroglycan, alpha-sarcoglycan, gamma-sarcoglycan and syntrophin as well as utrophin in the muscles of 13 Duchenne muscular dystrophy (DMD) carriers (with variable percentages of dystrophin-deficient fibers and with a range of clinical symptoms), 2 Becker muscular dystrophy (BMD) carriers (expressing a highly truncated protein in some fibers), 2 girls with a DMD-like phenotype, and 11 BMD carriers with almost normal dystrophin expression (reduced or patchy distribution in a few fibers only and rare dystrophin-deficient fibers). DAPs were highly reduced in all fibers lacking dystrophin in the DMD carriers, but were almost normal in the dystrophin-deficient fibers of the 2 BMD carriers with highly truncated dystrophin. In the 11 BMD carriers with nearly normal dystrophin, the few fibers with reduced or patchy dystrophin immunostaining also showed reduced DAP expression in correlation with dystrophin expression. Immunoblot for beta-dystroglycan and alpha-sarcoglycan confirmed the immunohistochemical findings. Utrophin expression was slightly increased in a proportion of fibers in the DMD and BMD carriers with dystrophin mosaicism. We found no correlation between utrophin expression and DAP expression. We conclude that absence or reduction of dystrophin in muscle fibers of DMD and BMD carriers causes a reduction of DAPs in the same fibers, as observed in DMD and BMD patients, while utrophin does not seem to play a role in DAP expression in adult muscle.

Mild clinical phenotype in a 12-year-old boy with partial merosin deficiency and central and peripheral nervous system abnormalities

We found partial merosin deficiency in a boy presenting at 12 yr with marked limb weakness and a waddling gait. Magnetic resonance imaging (MRI) showed the characteristic white matter abnormalities of merosin-negative congenital muscular dystrophy. There were also peripheral demyelinating polyneuropathy and evoked potential abnormalities. Unlike classic merosin-negative congenital muscular dystrophy, however, our patient was less hypotonic and weak and was able to achieve independent walking. Both by immunohistochemistry and Western blot merosin was shown to be moderately reduced. By immunostaining the alpha 1 laminin chain was overexpressed and beta 1 laminin chain was reduced. A spectrum of clinical phenotypes is likely to become evident in merosin-deficient patients in relation to the discovery of a range of molecular defects in, and variable expression of, this protein.

An unusual association: celiac disease and Becker muscular dystrophy

A history of poor growth in early childhood associated with persistent diarrhea and iron deficiency anemia led to a diagnosis of celiac disease in a 9-yr-old boy hospitalized for acute rhabdomyolysis. Elevated serum creatine kinase levels had been documented over the previous years, and Becker's muscular dystrophy was diagnosed by immunostaining of dystrophin and DNA analysis.

Clinical heterogeneity of adhalin deficiency

We report adhalin deficiency in 8 patients with clinically diagnosed muscular dystrophy, dystrophic histopathological features, high plasma creatine kinase levels, normal expression of dystrophin, and marked variability of symptoms. Although the distribution of hyposthenia was similar in all 8 patients and predominantly involved muscles in the pelvic girdle, age at onset and rate of disease progression were highly variable: In 2 patients onset, at ages 24 and 25, was later than has been previously observed. We found no apparent relation between disease severity and the quantity of adhalin expressed. Two kinds of myopathy with adhalin deficiency have been reported: one caused by a mutation in the adhalin gene on chromosome 17 (primary adhalinopathy) and the other linked to chromosome 13. The product of the gene on chromosome 13 is probably associated with adhalin and its deficiency results in secondary adhalinopathy. The severity of clinical phenotypes in these adhalinopathies seems to relate more to the kind and site of the mutations than to the residual amount of the protein. We also detected a variable reduction in the laminin beta 1 subunit by immunohistochemistry in most patients, confirming that this is commonly associated with adhalin deficiency.

Developmental expression of dystrophin, dystrophin-associated glycoproteins and other membrane cytoskeletal proteins in human skeletal and heart muscle

Dystrophin, utrophin and the dystrophin-associated glycoproteins, beta-dystroglycan and adhalin, were analyzed, together with the membrane cytoskeletal proteins beta-spectrin, vinculin and talin, and adult and fetal myosin heavy chains, in 25 normal human fetuses from 8 to 24 weeks of gestation. Dystrophin was present in heart and skeletal muscle from 8 weeks although in the latter was mainly in the cytoplasm at this stage. Utrophin expression increased until around gestational weeks 19/21, but by 24 weeks immunostaining and immunoblot band intensities had reduced. Beta-dystroglycan was scarce in skeletal muscle at 8 weeks, increased with maturation and was more abundant in heart of the same age. Adhalin appeared later than beta-dystroglycan on skeletal muscle fiber surfaces, positivity became more intense as the fibers matured. In heart adhalin was detectable only in groups of cells at 12-16 weeks. From 8 weeks all fetal myotubes expressed beta-spectrin on their surfaces, while vinculin and talin positivity was mainly at the periphery of the fascicles, increasing with age. Adult slow myosin was seen in most myotubes at 10 weeks. Secondary myotubes then formed which increasingly expressed adult fast myosin, while still retaining fetal myosin. By 24 weeks most fibers expressing adult slow myosin had lost fetal myosin and were more mature in the expression of most membrane proteins. Muscle membrane organization during human fetal development is a complex process and takes place earlier in heart than skeletal muscle.

DMD and BMD in the same family due to distinct mutations

We report on a family with a boy affected by Duchenne muscular dystrophy (DMD) and an asymptomatic cousin with a Becker-type dystrophin abnormality, diagnosed by chance. Dystrophin gene analysis showed that these conditions were caused by two distinct deletions with breakpoints in different exons. In Xp21 families, DNA analysis and dystrophin testing of asymptomatic males with high CK plasma levels might detect different dystrophin mutations in separate haplotypes as in our family, although we stress there should be clear clinical or familial indications for such testing.

Mutational analysis of muscle and brain specific promoter regions of dystrophin gene in DMD/BMD Italian patients by denaturing gradient gel electrophoresis (DGGE)

In order to characterize the nature of mutations occurring in non-deleted Duchenne (DMD) and Becker muscular dystrophy (BMD) affected males, a total of 40 unrelated Italian patients was studied for the presence of point mutations within the muscle-specific regulatory region of the dystrophin gene. We decided to investigate the dystrophin promoter sequences because nucleotide variations in these regions could impair the expression of the gene and be the underlying molecular defect in some forms of the disease. In four patients suffering from mental retardation, the brain promoter region was also studied. To screen for point mutations, we applied molecular analysis by parallel denaturing gradient gel electrophoresis (DGGE). No sequence alterations were found in either the muscle or the brain promoters, suggesting that mutations in these regions do not represent a common mechanism of mutation in DMD/BMD.

Identification of new mutations in the Emery-Dreifuss muscular dystrophy gene and evidence for genetic heterogeneity of the disease

The Emery-Dreifuss Muscular Dystrophy (EDMD) is an X-linked recessive muscular disorder characterized by early contractures of the elbows, Achilles tendons and postcervical muscles, slowly progressing muscle wasting and weakness and a cardiomyopathy characterized by conduction defects. Heart block is a frequent cause of death. Finding of mutations in one of the transcripts in the critical region in distal Xq28 led to the identification of the gene responsible for the disease. We now report the sequence of the gene which is 2100 bp long and the development of a set of primers to amplify and sequence the gene from patients' DNA. Eight unrelated X-linked familial cases were studied and they all carried different mutations, showing that lack of emerin in cardiac and skeletal muscle is the cause of the X-linked disease. No mutations were found in a family where the female carrier was affected nor in a sporadic case with a well established diagnosis of EDMD. Our findings suggest genetic heterogeneity of EDMD, and that at least two genes, the X-linked STA gene and one unidentified autosomal gene, are responsible for the disease.

Dystrophin characterization in BMD patients: correlation of abnormal protein with clinical phenotype

We have investigated protein expression and genotype in 59 Becker muscular dystrophy (BMD) patients. The aim was to identify possible causes of the marked variability in phenotype in patients with similar deletions/mutations. The patients were examined neurologically and functionally and underwent Manual Muscle Testing. Dystrophin expression was analysed by immunohistochemistry and western blot using antibodies against six different segments of the protein. DNA mutations were investigated by PCR amplification of 30 exons. Based on dystrophin expression at the sarcolemma, two groups of patients were identified: group A (29 patients) with the classic patchy distribution of dystrophin and group B (30 patients) with absence or reduction of one or more dystrophin portions and variable, although mostly normal, expression of the other portions of the protein. Dystrophin molecular weight was normal or slightly reduced in group A and was variably reduced, generally conspicuously so, in group B. The quantity of dystrophin expressed varied markedly in both groups. The pattern of immunohistochemical staining in group B patients correlated with milder clinical phenotype, suggesting that small dystrophin molecules lacking a portion in the N-terminus or in the rod domain, are more functional than proteins with normal or slightly reduced molecular weight that display the BMD-typical patchy distribution at the sarcolemma.

Expression of transforming growth factor-beta 1 in dystrophic patient muscles correlates with fibrosis. Pathogenetic role of a fibrogenic cytokine

Duchenne muscular dystrophy is a fatal disorder characterized by progressive muscular weakness, wasting, and severe muscle contractures in later disease stages. Muscle biopsy reveals conspicuous myofiber degeneration and fibrosis substituting muscle tissue. We quantitatively determined mRNA of the potent fibrogenic cytokine transforming growth factor-beta 1 by quantitative PCR in 15 Duchenne muscular dystrophy, 13 Becker muscular dystrophy, 11 spinal muscular atrophy patients, and 16 controls. Higher transforming growth factor-beta 1 expression was greater in Duchenne muscular dystrophy patients than controls (P = 0.012) and Becker patients (P = 0.03). Fibrosis was significantly more prominent in Duchenne muscular dystrophy than Becker muscular dystrophy, spinal muscular atrophy, and controls. The proportion of connective tissue in muscle biopsies increased progressively with age in Duchenne muscular dystrophy patients, while transforming growth factor-beta 1 levels peaked at 2 and 6 yr of age. Transforming growth factor-beta 1 protein was also detected by immunocytochemistry and immunoblotting. Our findings suggest that transforming growth factor-beta 1 stimulates fibrosis in Duchenne muscular dystrophy. Expression of transforming growth factor-beta 1 in the early stages of Duchenne muscular dystrophy may be critical in initiating muscle fibrosis and antifibrosis treatment could slow progression of the disease, increasing the utility of gene therapy.

Lack of mRNA and dystrophin expression in DMD patients three months after myoblast transfer

We report our experience on myoblast transplantation in three Duchenne muscular dystrophy patients. Pure myoblasts (55 x 10(6) per patient) from HLA-matched donors, were injected into a tibialis anterior and the controlateral muscle was sham injected. Three months after transplantation, biopsies from the injected muscles were negative for dystrophin expression by immunocytochemistry. Reverse transcriptase-PCR (RT-PCR) failed to amplify any fragments of the deleted regions. This result confirms that myoblast transplantation is feasible, although the efficacy of this therapeutic approach is poor.

Late-onset riboflavin-responsive myopathy with combined multiple acyl coenzyme A dehydrogenase and respiratory chain deficiency

We studied the effect of riboflavin treatment on the clinical status and on the activities of beta-oxidation and respiratory chain enzymes in a 69-year-old patient with late-onset myopathy. Before treatment, she was very weak and wasted in the limbs and trunk muscles; also, she could not walk or attend to daily activities. Marked lipid storage was present in the muscle biopsy. The activities of short-chain acyl coenzyme A (acyl-CoA) dehydrogenase (SCAD), medium-chain acyl-CoA dehydrogenase (MCAD), and long-chain acyl-CoA dehydrogenase (LCAD) in isolated muscle mitochondria were reduced to less than 10% of control values. This defect in fatty acid oxidation was associated with a marked deficiency of two flavin-dependent respiratory chain complexes: complex I activity was 20% and complex II activity was 25% of control values. By contrast, the activities of the nonflavin-dependent complex III and complex IV were normal. Western blot analysis of the patient's muscle mitochondrial extracts with antibodies raised against purified SCAD, MCAD, and the alpha- and beta-subunits of the electron transfer flavoprotein (ETF) showed absence of SCAD cross-reacting material (CRM), markedly decreased MCAD-CRM, and normal amounts of both alpha- and beta-ETF-CRM. After riboflavin treatment, the patient's clinical status dramatically improved and morphologic changes in muscle disappeared. SCAD activity increased to 55% of control values, whereas MCAD, LCAD, and complex I and complex II activities normalized. SCAD and MCAD immunoreactivity was restored to normal. On the basis of our experience and the data in the literature, we concluded that some lipid storage myopathies can show dramatic response to riboflavin.

Fetus-like dystrophin expression and other cytoskeletal protein abnormalities in centronuclear myopathies

We have investigated supposed maturational arrest of muscle in centronuclear myopathies (CNMs) by characterizing the expression of dystrophin, other cytoskeletal proteins, and fetal myosin in the muscle fibers of 9 CNM patients (4 sporadic, 3 familial, 2 adult sporadic). Dystrophin and beta-spectrin localized intracytoplasmically in centrally nucleated fibers. Talin and vinculin were normally expressed. Desmin was radially organized in several fibers in all patients. Scattered vimentinpositive fibers were found in 3 cases. Six myotonic dystrophy cases and 4 inflammatory myopathy cases with regenerating fibers were also studied: dystrophin and the membrane cytoskeletal proteins were normally expressed in the former; and dystrophin, spectrin, and vinculin were reduced in the latter. Intracytoplasmic dystrophin is further evidence of maturational arrest in CNMs. Spectrin and dystrophin codistribute in these pathological conditions as in normal muscle. We conclude that the altered cytoskeletal network found in CNMs likely plays a pathogenetic role in these conditions.

Bethlem myopathy: early-onset benign autosomal dominant myopathy with contractures. Description of two new families

Bethlem myopathy is an apparently rare early-onset benign autosomal dominant limb-girdle myopathy with contractures of the fingers. To determine whether this disorder is unrecognized rather than rare we used muscle computerized tomography (CT) and isokinetic muscle testing and assiduously sought contractures of the fingers in relatives of two patients with the disease. CT showed that muscle impairment was mild but more diffuse than clinically apparent and showed an unexpected progressive degeneration of lumbar paravertebral muscles. The isokinetic test showed that the quadriceps was more involved that the hamstrings. In addition we found that contractures of the last four fingers progressed centripetally with age from the distal interphalangeal joints to the wrist. As a result we proved that 15 of the 21 examined subjects had the disease, 7 of them being unaware that anything was amiss. Careful examination may reveal that Bethlem myopathy is more common than is now thought.

Lysosomal glycogen storage with normal acid maltase: a familial study with successful heart transplant

Lysosomal glycogen storage in muscle with normal acid maltase activity is a rare inherited condition characterized by cardiomyopathy, mental retardation and mild myopathy in males, but generally only cardiomyopathy in females. Three cases (index case, his sister and her son) are described in a family with at least two other affected members. The index case underwent a successful heart transplant. The sister has cardiac involvement, myopathic changes and mental impairment--to our knowledge the first report of multisystem involvement in a female. We propose that skeletal muscle should be examined in young patients with hypertrophic cardiomyopathy. Furthermore, female relatives of males with the disease should be investigated for cardiomyopathy; they would be excellent candidates for life-saving heart transplant, since myopathy and mental retardation, if clinically evident, are mild.

Dilated cardiomyopathy requiring cardiac transplantation as initial manifestation of Xp21 Becker type muscular dystrophy

A neurologically asymptomatic 32-yr-old man recently transplanted for end-stage dilated cardiomyopathy presented with progressively increasing serum creatine kinase level (hyperCKemia) while receiving cyclosporin and simvastatine treatment. Revised family history led to suspicion of X-linked inherited myopathy, then confirmed by muscle biopsy findings showing myopathic dystrophic changes, a patchy distribution of immunoreactivity on the sarcolemma of several muscle fibres with anti-dystrophin antibodies and a double dystrophin band of normal and lower molecular weight on immunoblot analysis. A molecular genetic study demonstrated a deletion spanning over exons 45-47 at Xp21 locus. Routine neurological evaluation and currently available laboratory investigation may lead to early diagnosis of otherwise unrecognized Xp21 BMD among patients presenting with dilated cardiomyopathy alone, thus avoiding subsequent diagnostic difficulties.

Immunohistochemical analysis of dystrophin-associated proteins in Becker/Duchenne muscular dystrophy with huge in-frame deletions in the NH2-terminal and rod domains of dystrophin

The absence of dystrophin causes the drastic reduction of the dystrophin-associated proteins (DAPs) in the sarcolemma and the loss of the linkage between the subsarcolemmal cytoskeleton and the extracellular matrix in Duchenne muscular dystrophy (DMD) skeletal muscle. Here, we report a mild reduction of the DAPs in the unique Becker muscular dystrophy patients with huge deletions in the rod domain of dystrophin and a moderate reduction of the DAPs in patients with huge deletions that involve both the NH2-terminal and rod domains of dystrophin. The phenotype of the latter patients was more severe than that of the former. In both cases, however, the reduction in the DAPs was milder than in typical DMD patients or DMD patients lacking the COOH-terminal domains of dystrophin. Our results suggest that (a) the NH2-terminal and rod domains of dystrophin may not be essential for the interaction with the sarcolemmal glycoprotein complex; and (b) defects in the actin binding activity of dystrophin may cause disruption of the anchorage of the dystrophin-glycoprotein complex to the subsarcolemmal cytoskeleton, which may render muscle fibers susceptible to degeneration.

Dystrophin abnormalities in Duchenne and Becker dystrophy carriers: correlation with cytoskeletal proteins and myosins

Characterization with a panel of six antibodies revealed abnormal dystrophin expression in 6 of 20 Duchenne muscular dystrophy (DMD) carriers examined, and in 5 of 12 Becker muscular dystrophy (BMD) carriers examined. The immunocytochemistry of muscle fibres was normal with five of the antibodies in two BMD carriers, but some muscle fibres were negative to the antibody directed against a portion of the dystrophin rod domain. Mosaicism was detected with all six antibodies in the other three BMD (but in only a small number of fibres) and in all DMD carriers muscles. Spectrin, vinculin and talin were immunolocalized in the same muscle specimens in order to assess membrane cytoskeletal integrity and to correlate their expression with that of dystrophin. These proteins, including vinculin, which was previously reported to be reduced in DMD patient muscles, were normally present on the surface of all dystrophin-deficient fibres. Muscle fibre types were characterized using monoclonal antibodies against fetal myosin and adult fast and adult slow myosin heavy chains. In both the DMD and BMD carriers, a significant reduction in type 2B fibres, as well as an increase in type 2C and fetal myosin-containing fibres was found - as has also been reported in DMD patients. Altered dystrophin expression was observed more frequently in type 2 than type 1 fibres. Dystrophin deficiency was found in a high percentage of type 2C fibres as well as in all fibres expressing fetal myosin; this suggests that dystrophin-deficient fibres are more susceptible to degeneration, leading to regeneration.