Primary adhalin deficiency as a cause of muscular dystrophy in patients with normal dystrophin

In our experience, more than half of muscular dystrophy patients show a primary dystrophinopathy. The underlying cause of muscular dystrophy in the vast majority of patients with normal dystrophin is unknown. Recently, a French family with 4 young siblings showing a muscular dystrophy of unknown progression was shown to have a primary deficiency of ?adhalin,”? the 50-kd dystrophin-associated protein. Here we report the screening of the entire adhalin coding sequence in muscle biopsy specimens from 30 muscular dystrophy patients to (1) determine whether adhalin deficiency is restricted to the French population, (2) determine the incidence of adhalin deficiency in muscular dystrophy patients, and (3) characterize the clinical features and mutations in adhalin-deficient patients. We identified a single African-American girl with childhood-onset muscular dystrophy and adhalin gene mutations. We found her to be a compound heterozygote for two different mutations of the same amino acid (Arg98Cys; Arg98His), one of which was previously identified in the French family. Our results suggest that primary adhalin deficiency in patients with muscular dystrophy but normal dystrophin is relatively infrequent, and that adhalin-deficient patients are not restricted to the French population.     

Duplication of dystrophin gene and dissimilar clinical phenotype in the same family

We report here three related patients with a duplication of exons 19–41 of the dystrophin gene, having dissimilar clinical phenotype and dystrophin immunohistochemistry. Two brothers aged six and three years had myalgia, proximal muscular weakness and hypertrophic calves, with 10- to 20-fold increase of serum creatine kinase. Muscle biopsy showed dystrophic changes and reduced, patchy binding of dystrophin. The clinical and laboratory findings were consistent with a diagnosis of Becker muscular dystrophy with early onset. Their 14-year-old cousin had only mild hyperCKemia. His muscle biopsy was normal with only mild reduction of dystrophin immunostaining. At follow-up, he is still without symptoms and signs at age 19. All three patients had the same gene duplication and an increased dystrophin size of 507 kDa. Expression of the dystrophin-associated glycoproteins adhalin, -dystroglycan, and, β-dystroglycan were normal in the three patients. An intrafamilial variability in patients carrying a partial duplication of the dystrophin gene may be related to a quantitative difference in mRNA.     

Sarcolemmal Alpha and Gamma Sarcoglycan Protein Deficiencies in Turkish Siblings With a Novel Missense Mutation in the Alpha Sarcoglycan Gene

BackgroundThe sarcoglycan alpha gene, also known as the adhalin gene, is located on chromosome 17q21; mutations in this gene are associated with limb-girdle muscular dystrophy type 2D. We describe two Turkish siblings with findings consistent with limb-girdle muscular dystrophy type 2D. The evaluation excluded a dystrophinopathy, which is the most common form of muscular dystrophy.PatientsBoth siblings had very high levels of creatinine phosphokinase and negative molecular tests for deletions and duplications of the dystrophin gene. The older boy presented at 8 years of age with an inability to climb steps and an abnormal gait. His younger brother was 5 years old and had similar symptoms. The muscle biopsy evaluation was performed only in the older brother.ResultsThe muscle biopsy showed dystrophic features as well as a deficiency in the expression of two different glycoproteins: the alpha sarcoglycan and the gamma sarcoglycan. Sarcolemmal expressions of dystrophin and other sarcoglycans (beta and delta) were diffusely present. DNA analysis demonstrated the presence of previously unknown homozygous mutations [c.226 C > T (p.L76 F)] in exon 3 in the sarcoglycan alpha genes of both siblings. Similar heterozygous point mutations at the same locus were found in both parents, but the genes of beta, delta, and gamma sarcoglycan were normal in the remaining family members.ConclusionsWe describe two siblings with limb-girdle muscular dystrophy type 2D with a novel missense mutation. These patients illustrate that the differential diagnosis of muscular dystrophies is impossible with clinical findings alone. Therefore, a muscle biopsy and DNA analysis remain essential methods for diagnosis of muscle diseases.     

Congenital muscular dystrophy with severe retrocollis and mental retardation: a report of two siblings.

Two siblings with a congenital muscular dystrophy and severe mental retardation which was not due to dystrophin, merosin, or adhalin deficiency are described. These cases overlap with congenital muscular dystrophy of the Fukuyama-type but are less severe. Atypical features include limited facial involvement, retained ambulation, and severe retrocollis.     

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 β1 subunit by immunohistochemistry in most patients, confirming that this is commonly associated with adhalin deficiency.     

Duchenne phenotype with in-frame deletion removing major portion of dystrophin rod: Threshold effect for deletion size?

In a 9-year-old boy with Duchenne muscular dystrophy we found a large in-frame deletion, spanning exons 10 to 53 of the dystrophin gene. The deletion removed almost all of the central rod domain of dystrophin. Using carboxyterminal dystrophin antibodies the immunohistochemical reaction was normal in all muscle fibers. In immunoblot studies we found dystrophin of abnormal size (160 kDa) and normal amount (about 100%). The immunochemical features and the reading frame deduced from DNA analysis are usually associated with Becker muscular dystrophy, but the clinical characteristics were those of the severe Duchenne phenotype. All the cases of in-frame dystrophin deletions reported so far, which involved more than 36 exons, invariably resulted in a severe phenotype. Therefore, a threshold effect for dystrophin length may be reasonably suspected. Very short dystrophin molecules might induce a severe disarray of the dystrophin network. © 1996 John Wiley & Sons, Inc.     

Duchenne型肌营养不良的临床和病理及抗肌萎缩蛋白表达

目的：归纳总结Duchenne型肌营养不良（DMD）的临床表现,组织病理特点及抗肌萎缩蛋白表达情况。方法：通过临床、病理及免疫组化染色方法,对16例DMD患者的临床表现,肌肉病理改变和肌肉抗肌萎缩蛋白表达情况进行观察分析。结果：年龄〉4岁的14例患儿均有比较典型的DMD临床表现;而年龄〈4岁的2例患儿症状较轻。肌肉病理显示2例为早期改变、11例为中期改变、3例为晚期改变,病理改变严重程度与年龄相关。免疫组化染色显示16例患者的肌肉标本抗肌萎缩蛋白均完全缺失。结论：DMD患者的临床和病理表现的严重程度与年龄有关,检查抗肌萎缩蛋白在肌纤维膜上表达是诊断DMD的金标准。     

Deficiency of the 50 kDa dystrophin-associated-glycoprotein (adhalin) in an Indian autosomal recessive limb girdle muscular dystrophy patient : immunochemical analysis and clinical aspects

Abnormalities of dystrophin are a common cause of muscular dystrophy and testing for dystrophin gene or protein has become a part of routine diagnostic evaluation of patients who present with progressive proximal muscle weakness, high serum creatine kinase concentrations, and histopathological evidence of a dystrophic process. Patients who have no dystrophin abnormalities are assumed to have autosomal recessive muscular dystrophy. In a family consisting of 5 sibs, 2 mentally normal brothers presented with abnormal gait and protrusion of chest and hips. Muscle biopsy from one of them showed dystrophic changes and reduced patchy binding of dystrophin. No detectable deletion was observed in the patient's DNA and his brother with cDMD probes. Dystrophin associated proteins, beta-dystroglycan showed discontinuous immunostaining in the sarcolemma and alpha-sarcoglycan (adhalin) was totally absent, while beta-, gamma-, and delta-sarcoglycans were highly reduced. Immunoblot analysis showed dystrophin of normal molecular weight but of decreased quantity, beta-dystroglycan was reduced by about 37% while alpha-sarcoglycan was completely absent. This study is a first attempt for a systematic clinical, genetic and molecular investigation of the autosomal recessive LGMD in India.     

Electron microscopic observations of triple immunogold labelling for dystrophin, β-dystroglycan and adhalin in human skeletal myofibers

Dystrophin is the Duchenne muscular dystrophy gene product and is a membrane cytoskeletal protein present in the network of the plasma membrane undercoat. Adhalin (50 kDa dystrophin-associated glycoprotein) and β-dystroglycan (43 kDa dystrophin-associated glycoprotein) are the transmembrane components of the normal muscle plasma membrane, and β-dystroglycan has been demonstrated to bind dystrophin at the inside surface of normal muscle plasma membrane. This investigation was undertaken to test whether the epitopes of dystrophin, β-dystroglycan and adhalin are closely associated with each other by using triple immunogold labelling electron microscopy on normal human skeletal myofibers. Although closely associated signals of triplet immunogold particles were observed, there were less numerous than expected. However, closely associated signals of two epitopes of dystrophin and β-dystroglycan, dystrophin and adhalin, or adhalin and β-dystroglycan were frequently observed. These ultrastructural findings are consistent with biochemical evidence implying that dystrophin, β-dystroglycan and adhalin are closely associated with each other at the normal muscle plasma membrane. Received: 15 January 1996 / Revised, accepted: 1 April 1996     

Improved diagnosis of Becker muscular dystrophy by dystrophin testing

We assessed the quantity (relative cellular abundance) and quality (approximate molecular weight) of dystrophin in muscle biopsies from 97 patients with a diagnosis of possible Becker muscular dystrophy. Fifty-four (all male) had dystrophin abnormalities and were deemed to have true Becker muscular dystrophy. The other 43 patients (14 female, 29 male) had no detectable dystrophin abnormalities. Of the dystrophin-verified Becker dystrophy patients, 35% (19/54) had a family history consistent with X-linked recessive inheritance. On the other hand, none of the 43 patients with apparently normal dystrophin had a clear X-linked family history, suggesting that few of these 43 actually had a form of Becker dystrophy. The data suggest that of all patients with a clinical picture consistent with Becker dystrophy but no family history, about 60% will be true Becker patients. The correlation of both the biochemical and clinical data suggests that Duchenne/Becker dystrophy can be divided into 4 clinically useful categories: Duchenne dystrophy (wheelchair at about age 11 years; dystrophin quantity less than 3% of normal); severe Becker dystrophy (wheelchair age 13 to 20 years; dystrophin 3% to 10%); and moderate/mild Becker dystrophy (wheelchair greater than 20 years; dystrophin quantity greater than or equal to 20%). Given the observed clinical variability of Becker dystrophy, it appears that dystrophin analysis is required for accurately distinguishing between Becker dystrophy and clinically similar autosomal recessive myopathies.     

Duchenne muscular dystrophy in Tunisia: a clinical and morphological study of 77 cases.

Two types of progressive muscular dystrophy occur in Tunisian children. The first type is characterized by normal dystrophin assays and affects girls and boys in an autosomal recessive pattern of inheritance. The second type has the features of the typical Duchenne muscular dystrophy (DMD) and has abnormal dystrophin. Between 1974 and 1986, 77 patients with Duchenne muscular dystrophy were examined, 66 were biopsied. Among affected siblings and within family kindreds, we observed both clinical and histopathological variability. However, there was a close correlation between the clinical condition and the biopsy findings in each case, allowing accurate prediction of the patient's course and probable duration of the disease.     

Prenatal Diagnosis of BMD in Morocco: Evolution and Limits

The muscular dystrophy is a group of inherited disorders characterized in the most of cases by progressive muscle weakness. The best known are X-linked disorder Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD). BMD is a milder form of the disease with a later age of onset and a slower clinical progression. The DMD gene, located on Xp21, is the largest human gene in the human genome (2.3 Mb). DMD gene consists of 79 exons and codes for dystrophin protein. A 9-year-old boy, who experienced symptoms of the disease, was admitted to the Casablanca University Children’s Hospital. The patient, with no known family history of significant muscle disease, was first examined at 4 years of age because of walking difficulties and a limited hands force. Blood tests revealed elevated serum levels of creatine kinase (7.60 U/L). The electromyogram showed myopathic changes, consisting of polyphasic potentials, and the muscular biopsy revealed dystrophic aspect. Analysis of the dystrophin-encoding gene by PCR deletion analysis of the dystrophin gene was performed by multiplex PCR primer sets of Chamberlain and Beggs. The analysis showed a deletion of exons 45 to 49. Mother genetic testing showed the heterozygosis deletion.     

Heterogeneity of dystrophin expression in patients with Duchenne and Becker muscular dystrophy

Summary This report documents the results of an integrated biochemical and immunocytochemical investigation into the expression of dystrophin (the protein product of the Duchenne muscular dystrophy gene) in muscle biopsies from 226 patients. It is the first study in which dystrophin has been analysed on blots and on tissue sections in such a large number of patients using the same (monoclonal) antibody. The 140 patients with Xp21 muscular dystrophy who were included in this study represent a continuous spectrum of disease severity and this range was reflected in the heterogeneity of dystrophin expression which was observed with respect to abundance, size and the pattern of tissue localisation. Approximately 40% of biopsies obtained from patients diagnosed as having Duchenne muscular, dystrophy (DMD) contained isolated clearly positive fibres and a further 20% had very weak labelling on a large number of fibres. Biopsies from patients with Becker muscular dystrophy (BMD) showed labelling patterns which varied from weak labelling on the majority of fibres to clear labelling on all fibres. Typically, however, there was inter-and intra-fibre variation in labelling intensity. Approximately 85% of the 52 BMD and 54 DMD patients who had unequivocal labelling on blots demonstrated a protein of abnormal size. The remaining 15% had a protein of normal size but reduced abundance. Overall, the estimated abundance of dystrophin correlated well with clinical assessments of the disease severity expressed in patients: We conclude that dystrophin analysis is an essential and dependable technique for the differential diagnosis of patients with Xp21 muscular dystrophy.Supported by the University of Newcastle-upon-Tyne Research Committee, the Muscular Dystropy Group of Great Britain and the Medical Research Council     

Myopathy,Unique Clinical Features,and Brain Malformations Mimicking Fukuyama Congenital Muscular Dystrophy: A Case Report

The pathological findings of an adult woman and clinical features of her brothers identified a new type of congenital muscular dystrophy with brain malformation. The 40-year-old woman, born to parents who were first cousins, was retarded in both mental and physical development from early infancy. She had a monkey-like face with macroglossia, dwarfism, decreased subcutaneous fat with hard skin, joint contracture, and muscular atrophy and weakness with myopathic changes, but she was able to walk until the age of 31 years. Two brothers showed clinical features more or less similar to hers, but their mental and physical development was not severely retarded. Autopsy of the patient revealed that the brain malformation consisted of micropolygyria and pachygyria, and the muscular atrophy was of the normal dystrophin type. In addition, presenile occurrence of Alzheimer's neurofibrillary tangles was prominent in the malformed brain. The overall picture was that of congenital muscular dystrophy of the Fukuyama type, demonstrating an adult variant of the disease.     

Early onset autosomal dominant progressive muscular dystrophy presenting in childhood as a Becker phenotype--the importance of dystrophin and molecular genetic analysis.

We present two cases of autosomal dominant limb girdle muscular dystrophy in a father and son. Both presented in childhood with a classical Becker muscular dystrophy phenotype. The father had initially been informed that he would not have affected children. After the diagnosis of muscular dystrophy in the son, immunoblot analysis was performed on muscle and revealed normal dystrophin. The polymerase chain reaction did not show any deletions in the dystrophin gene, and the father's dystrophin gene was not passed to his son. These cases demonstrate that autosomal dominant muscular dystrophy may present in childhood, and that dystrophin and molecular genetic analyses should be performed when considering the diagnosis of childhood muscular dystrophy, even in the presence of a classical phenotype.     

Diagnosis of dystrophinopathy by skin biopsy

We studied the expression of dystrophin in skin biopsy samples from 19 patients with neuromuscular diseases. Immunohistochemical procedures for dystrophin analyses were performed using monoclonal antibodies for three different domains. Arrector pili muscles, which are smooth muscles in the skin, expressed dystrophin in the patients with limb-girdle muscular dystrophy (5), facioscapulohumeral muscular dystrophy (1), and spinal muscular atrophy (3), and in normal controls (2). The C-terminus of dystrophin was slightly expressed in the patients with Duchenne muscular dystrophy, whereas the rod domain and N-terminus were absent. In one patient with Becker muscular dystrophy, the expression of dystrophin was reduced. The mosaic of dystrophin positive and negative smooth muscle fibers was observed in a manifesting carrier of Duchenne muscular dystrophy. Our results suggest that skin biopsy is very useful for the diagnosis of Duchenne/Becker muscular dystrophy and manifesting carrier of Duchenne muscular dystrophy, and can be performed even at an advanced stage of the disease.     

Abnormal dystrophin expression in patients with limb girdle syndromes

Clinical differential diagnosis between Becker muscular dystrophy (BMD) and limb gridle muscular dystrophy (LGMD) may be difficult because the BMD clinical phenotype tends to overlap with other limb girdle syndromes, especially with LGMD. Therefore we studied the expression of dystrophin, the protein product of the Becker and Duchenne muscular dystrophy gene, in muscle biopsy specimens of 30 patients (18 males, of whom 15 represented spradic cases, and 12 females) diagnosed as having LGMD according to traditional clinical, electrophysiological and histological criteria. For dystrophin analysis, six different monoclonal antibodies directed against different epitopes of the dystrophin molecule were used. Immunocytochemically, five of the 30 LGMD patients (17%) showed abnormal dystrophin staining patterns diagnostic of BMD. Western blotting in these five patients, all sporadic cases, showed dystrophin of reduced size and/or abundance. Analysis of blood or muscle DNA using multiplex polymerase chain reaction revealed deletions in the dystrophin gene in three of the five. Thus, 5 of 15 (33%) sporadic male patients previously thought to have LGMD were identified as having BMD.     

Limb-girdle syndrome: a genetic study of 22 large Brazilian families. Comparison with X-linked Duchenne and Becker dystrophies

The differential clinical diagnosis between the X-linked muscular dystrophies (DMD and BMD) and autosomal recessive limb-girdle muscular dystrophy (LGMD), which is extremely important for genetic counseling, may be very difficult. The aim of the present report is to describe clinical and laboratory findings in patients from large families, with AR inheritance, in an attempt to characterize better cases which have been diagnosed as LGMD compared with the X-linked forms. The main features analysed are: age of onset and of confinement to a wheelchair, reproductive performance, serum enzymes (CK and PK) and dystrophin assessment (through immunohistochemistry and Western blot). Twenty-two families, with 62 affected patients diagnosed as limb-girdle muscular dystrophy, were included in this report. In 19 families, the patients had a milder clinical course, while in the remaining 3, the progression of the disease was continuous and clinically similar to X-linked DMD ("DMD-like"). A high consanguinity rate was observed among the parents of the affected patients (77%). No major clinical difference was observed between the X-linked and the AR forms. However, muscle dystrophin was found qualitatively and quantitatively normal in the autosomal forms but absent or abnormal in the X-linked ones. The reproductive performance was significantly higher for male than female patients. In addition, a surprising finding was the significantly greater fitness estimated for male LGMD cases as compared with Becker patients of comparable age studied in our center. The implications of such findings are discussed.     

Phenotype of combined Duchenne and facioscapulohumeral muscular dystrophy

This case report describes a young boy with concomitant genetically-confirmed Duchenne muscular dystrophy and facioscapulohumeral muscular dystrophy with a novel dystrophin mutation in exon 6 and a D4Z4 fragment of 31 kb. This child presented with a more severe phenotype than expected for either individual disease process and underscores the role for thorough diagnostic investigation in identifying atypical clinical presentations.     

Merosin-positive congenital muscular dystrophy: a large inbred family

Large families with congenital muscular dystrophy are rare. We report a clinical, histopathological, immunocytochemical, electrophysiological, radiological and genetic study of 10 cases affected by "pure" CMD belonging to two generations of a large inbred Palestinian family. The disease showed autosomal recessive inheritance. All patients had generalised muscular weakness and hypotonia at birth without arthrogryposis. They had a relatively benign clinical course with stabilisation of the clinical picture at different ages and at variable degrees of severity. The pattern of muscle weakness and wasting was more marked in the proximal upper limb-girdle and trunk muscles. Lower limb muscles were more mildly involved. Serum CK was normal or moderately increased. All patients had normal intelligence, normal computed tomography (CT) scans of the brain and normal somatosensory evoked potentials (SEP). Electromyography (EMG) and muscle biopsy showed morphological changes compatible with muscular dystrophy. Immunocytochemistry for dystrophin, laminin alpha 2 of merosin, and for alpha, beta, gamma sarcoglycans was normal. Linkage analysis excluded all the known loci for CMD, including laminin alpha 2 on chromosome 6q2, the Fukuyama congenital muscular dystrophy locus on 9q3, the integrin alpha 7 locus on chromosome 12q13 and the recently identified locus on 1p35-36. The family we present is clinically and genetically distinct from the already mapped forms of congenital muscular dystrophy. Genetic studies are in progress to localise the gene responsible for this condition.