Cardiopulmonary dysfunction in patients with limb‐girdle muscular dystrophy 2A

Introduction: Little is known about the frequency of cardiopulmonary failure in limb‐girdle muscular dystrophy type 2A (calpainopathy) patients, although some studies have reported severe cardiomyopathy or respiratory failure. Methods: To clarify the frequency of cardiopulmonary dysfunction in this patient population, we retrospectively reviewed the respiratory and cardiac function of 43 patients with calpainopathy. Results: Nine of the 43 patients had forced vital capacity (FVC) < 80%, and 3 used noninvasive positive pressure ventilation. Mean FVC was significantly lower in patients who were nonambulant and had normal creatine kinase levels. Only 1 patient had a prolonged QRS complex duration. Echocardiography revealed that 1 patient had very mild left ventricular dysfunction. Conclusions: These findings suggest that patients with calpainopathy may develop severe respiratory failure, but cardiac dysfunction is infrequent. Muscle Nerve 55 : 465–469, 2017     

Diagnosis of limb‐girdle muscular dystrophy 2A by immunohistochemical techniques

The Western blot technique is currently the standard detection method for suspected limb girdle muscular dystrophy (LGMD) 2A (calpainopathy). This is the first report in the English literature of the successful application of immunohistochemical techniques to support a diagnosis of LGMD 2A. This approach is straightforward and appears to be reasonably specific. We propose that immunohistochemical methods should be re‐evaluated for the screening of undiagnosed patients with suspected LGMD 2A.     

LAMA2‐related myopathy: Frequency among congenital and limb‐girdle muscular dystrophies

Introduction: Muscular dystrophy caused by LAMA2‐gene mutations is an autosomal recessive disease typically presenting as a severe, early‐onset congenital muscular dystrophy (CMD). However, milder cases with a limb‐girdle type muscular dystrophy (LGMD) have been described. Methods: In this study, we assessed the frequency and phenotypic spectrum of LAMA2‐related muscular dystrophy in CMD (n = 18) and LGMD2 (n = 128) cohorts identified in the last 15 years in eastern Denmark. The medical history, brain‐MRI, muscle pathology, muscle laminin‐α2 expression, and genetic analyses were assessed. Results: Molecular genetics revealed 2 pathogenic LAMA2 mutations in 5 of 18 CMD and 3 of 128 LGMD patients, corresponding to a LAMA2‐mutation frequency of 28% in the CMD and 2.3% in the LGMD cohorts, respectively. Conclusions: This study demonstrates a wide clinical spectrum of LAMA2‐related muscular dystrophy and its prevalence in an LGMD2 cohort, which indicates that LAMA2 muscular dystrophy should be included in the LGMD2 nomenclature. Muscle Nerve 52: 547–553, 2015     

Entire CAPN3 gene deletion in a patient with limb‐girdle muscular dystrophy type 2A

Limb‐girdle muscular dystrophy type 2A (LGMD2A) due to mutations in the CAPN3 gene is one of the most common of autosomal recessive limb‐girdle muscular dystrophies. We describe a patient who had a typical LGMD2A phenotype and posterior compartment involvement on MRI. Different genetic analyses were performed, including microarray analysis. There was an apparently homozygous mutation in exon 24, c.2465G>T, p.(*822Leuext62*), and a lack of correlation in the disease segregation analyses. This suggested the presence of a genomic rearrangement. In fact, a heterozygous deletion of the entire CAPN3 gene was found. This novel deletion comprised the terminal region of the GANC gene and the entire CAPN3 gene. This finding points out the need to reconsider and adapt our current strategy of molecular diagnosis in order to detect these types of genomic rearrangements that escape standard mutation screening procedures. Muscle Nerve 50 : 448–453, 2014     

Dysferlin aggregation in limb‐girdle muscular dystrophy type 2B/myoshi myopathy necessitates mutational screen for diagnosis

Introduction: Diagnosis of the limb‐girdle muscular dystrophies (LGMDs) has been facilitated by the use of immunofluorescence microscopy, Western blot analysis, and rapid genetic testing. Methods: We identified 7 patients with LGMD2B or Miyoshi myopathy (MM) phenotypes and performed detailed history, physical examination, and mutation analyses of genomic DNA. Results: Ten disease‐causing variants of the dysferlin gene (DYSF) were detected, 4 of which were novel and predicted to be pathogenic (IVS33+9G>T, c.1343T>C, c.4747T>G, and c.5066dupC). Two of these mutations (c.1343T>C and IVS33+9G>T) were associated with a reduction in sarcolemmal dysferlin expression, despite increased total mRNA and protein in mixed muscle homogenates, due to a pathological retention of the mutated polypeptide in the cytoplasm. Conclusions: Considering that protein‐based assays may yield false negative test results and that dysferlin aggregation may be present in other LGMDs, mutational screening is necessary for specific diagnosis in primary dysferlinopathy patients exhibiting this phenotype. Muscle Nerve 47: 740–747, 2013     

Limb girdle muscular dystrophy: Description of a phenotype

The phenotype is reported of 20 patients with autosomal recessive or sporadic, pelvifemoral limb girdle muscular dystrophy (LGMD). Selective wasting of muscles was observed at the moderately advanced stage of illness. The pattern of weakness was uniform. Attention to clinical detail allowed the identification of a phenotype different from a hypothetical scheme of LGMD based on previous literature, and other causes of limb girdle weakness. These patients may represent yet another nosologic entity within the autosomal recessive dystrophies; molecular genetic studies are awaited. A limited magnetic resonance imaging (MRI) study of muscle was of little consequence. Although additional detail was obtained, no pathognomonic distribution of the dystrophic process was observed; interindividual variation existed even among closely matched siblings. The severity of MRI signal change did not consistently correlate with the degree of weakness in an individual. When a diagnosis is uncertain, however, the added detail may be useful. © 1994 John Wiley & Sons, Inc.     

Limb girdle muscular dystrophy: A pathological and immunohistochemical reevaluation

Ninety-seven muscle biopsies from 81 limb girdle muscular dystrophy (LGMD) patients [32 autosomal recessive (AR), 15 autosomal dominant (AD), 34 sporadic] were morphologically reevaluated. Sarcoglycan analysis was done in 37 available muscle biopsies of AR and sporadic patients. Chi-square tests were used to analyze the relation between abnormalities in AR/sporadic versus AD cases. Eighty percent of the muscle biopsies showed a predominantly dystrophic pattern, 20% showed myopathic changes, and 17% of these also had neurogenic changes. Muscle histology was not significantly different between AR/sporadic and AD LGMD; however, the observed abnormalities were more pronounced in the AR/sporadic group. Collections of inflammatory cells were observed in 25% and 10% of the AR/sporadic and AD group, respectively. Sarcoglycanopathy was diagnosed in 25% of the AR and sporadic patients of the 37 families tested. We conclude that the histological picture of AR/sporadic and AD LGMD is essentially the same, and sarcoglycanopathy constitutes an important part of the AR/sporadic patients. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:584–590, 1998.     

Spin-lock magnetic resonance imaging of muscle in patients with autosomal recessive limb girdle muscular dystrophy.

Spin-lock imaging is a new magnetic resonance imaging (MRI) technique used to reflect the microstructural integrity of muscle. The purpose of this study was to characterize spin-lock contrast (SLC) of calf muscles in limb girdle muscular dystrophy (LGMD). The calf muscles of 5 patients with LGMD and 10 healthy volunteers were imaged with an off-resonance magnetic resonance (MR) spin-lock suppression pulse. Spin-lock suppression ratios were calculated for anterior tibialis, posterior tibialis, soleus, and gastrocnemius muscles. Clinical assessments of muscle strength were compared to the spin-lock suppression ratios in the LGMD group. Strong SLC was observed in healthy muscles, with mean (+/- SD) suppression ratios ranging from 51.2% (+/- 3.6%) to 56.3% (+/- 1.3%). In diseased muscle, spin-lock signal suppression was reduced by 8%-70%, demonstrating an inverse correlation between symptom duration and suppression ratios. Spin-lock contrast in the patients with LGMD, as a reflection of tissue integrity, was best preserved in posterior tibialis, anterior tibialis, soleus, and gastrocnemius muscles in descending order. Clinical assessments did a poorer job of differentiating than SLC did and were in poor agreement with spin-lock suppression ratios. Spin-lock MRI can quantify microstructural changes in LGMD and appears to provide information not obtainable from clinical evaluations. This suggests that this noninvasive technique may be useful in evaluating the extent, progression, and response to therapy of LGMD.     

Protein and genetic diagnosis of limb girdle muscular dystrophy type 2A: The yield and the pitfalls

Limb girdle muscular dystrophy type 2A (LGMD2A) is the most frequent form of LGMD worldwide. Comprehensive clinical assessment and laboratory testing is essential for diagnosis of LGMD2A. Muscle immunoblot analysis of calpain‐3 is the most useful tool to direct genetic testing, as detection of calpain‐3 deficiency has high diagnostic value. However, calpain‐3 immunoblot testing lacks sensitivity in about 30% of cases due to gene mutations that inactivate the enzyme. The best diagnostic strategy should be determined on a case‐by‐case basis, depending on which tissues are available, and which molecular and/or genetic methods are adopted. In this work we survey the current knowledge, advantages, limitations, and pitfalls of protein testing and mutation detection in LGMD2A and provide an update of genetic epidemiology. Muscle Nerve 52 : 163–173, 2015     

Body weight‐supported training in Becker and limb girdle 2I muscular dystrophy

Introduction: We studied the functional effects of combined strength and aerobic anti‐gravity training in severely affected patients with Becker and Limb‐Girdle muscular dystrophies. Methods: Eight patients performed 10‐week progressive combined strength (squats, calf raises, lunges) and aerobic (walk/run, jogging in place or high knee‐lift) training 3 times/week in a lower‐body positive pressure environment. Closed‐kinetic‐chain leg muscle strength, isometric knee strength, rate of force development (RFD), and reaction time were evaluated. Results: Baseline data indicated an intact neural activation pattern but showed compromised muscle contractile properties. Training (compliance 91%) improved functional leg muscle strength. Squat series performance increased 30%, calf raises 45%, and lunges 23%. Conclusions: Anti‐gravity training improved closed‐kinetic‐chain leg muscle strength despite no changes in isometric knee extension strength and absolute RFD. The improved closed‐kinetic‐chain performance may relate to neural adaptation involving motor learning and/or improved muscle strength of other muscles than the weak knee extensors. Muscle Nerve 54 : 239–243, 2016     

A new mutation of the fukutin gene causing late-onset limb girdle muscular dystrophy

Defects in glycosylations of α-dystroglycan are associated with mutations in several genes, including the fukutin gene (FKTN). Hypoglycosylation of α-dystroglycan results in several forms of muscular dystrophy with variable phenotype. Outside Japan, the prevalence of muscular dystrophies related to aberrations of FKTN is rare, with only eight reported cases of limb girdle phenotype (LGMD2M). We describe the mildest affected patient outside Japan with genetically confirmed LGMD2M and onset of symptoms at age 14. She was brought to medical attention at age 12, not because of muscle weakness, but due to episodes of tachycardia caused by Wolff–Parkinson–White syndrome. On examination, she had rigid spine syndrome, a typical limb girdle dystrophy pattern of muscle weakness, cardiomyopathy, and serum CK levels >2000 IU/L (normal <150 IU/L). A homozygous, novel c.917A>G; p.Y306C mutation in the FKTN gene was found. The case confirms FKTN mutations as a cause of LGMD2M without mental retardation and expands the phenotypic spectrum for LGMD2M to include cardiomyopathy and rigid spine syndrome in the mildest affected non-Japanese patient reported so far.