Diagnosis Of Limb-girdle Muscular Dystrophy Research Articles

Molecular Diagnosis of Limb-Girdle Muscular Dystrophy Using Next-Generation Sequencing Panels

Introduction: Limb-girdle muscular dystrophies (LGMDs) are clinically and genetically heterogeneous muscle disorders. We aimed to share the diagnostic yield of an NGS gene panel containing LGMD-related genes and our experience with LGMD. Methods: Between February 2019 and October 2022, patients with a suspicion of LGMD and their relatives were reviewed in terms of demographic, clinical, and individual genetic data, age of symptom onset, sex, clinical features, LGMD types, cardiac involvement, muscle biopsy results, family history, and consanguinity. Our NGS gene panel consisted of ANO5, CAPN3, CAV3, DAG1, DES, DNAJB6, DYSF, FKTN, FLNC, FRKP, GAA, GMPPB, HNRNPDL, ISPD, LIMS2, LMNA, MYOT, PLEC, POMGNT1, POMK, POMT1, POMT2, SGCA, SGCB, SGCD, SGCG, TCAP, TNPO3, TRAPPC11, TRIM32, and TTN genes. Results: The diagnosis rate was 61.1% (11/18). Twelve (80%) patients with LGMD were male and three (20%) were female. The median age was 15.9 (range, 1.5–39) years. Our patient collective was drawn up out of patients with the following variants: LGMDR1 (n = 6; 40%), LGMDR2 (n = 4; 26.6%), LGMDR3 (n = 4; 26.6%), and LGMDR12 (n = 1; 6.7%). Conclusion: The present study showed that the NGS panel has a high success rate in the diagnosis of LGMD and contributes to early diagnosis.

Combined sequence and copy number analysis improves diagnosis of limb girdle and other myopathies.

Clinical and genetic heterogeneities make diagnosis of limb-girdle muscular dystrophy (LGMD) and other overlapping disorders of muscle weakness complicated and expensive. We aimed to develop a comprehensive next generation sequence-based multi-gene panel ("The Lantern Focused Neuromuscular Panel") to detect both sequence variants and copy number variants in one assay. Patients with clinical diagnosis of LGMD or other overlapping muscular dystrophies in the United States were tested by PerkinElmer Genomics in 2018-2021 via "The Lantern Project," a sponsored diagnostic testing program. Sixty-six genes related to LGMD subtypes- and other myopathies were investigated. Main outcomes were diagnostic yield, gene-variant spectrum, and LGMD subtypes' prevalence. Molecular diagnosis was established in 19.6% (1266) of 6473 cases. Major genes contributing to LGMD were identified including CAPN3 (5.4%, 68), DYSF (4.0%, 51), GAA (3.7%, 47), ANO5 (3.6%, 45), and FKRP (2.7%, 34). Genes of other overlapping MD subtypes identified included PABPN1 (10.5%, 133), VCP (2.2%, 28), MYOT (1.2% 15), LDB3 (1.0%, 13), COL6A1 (1.5%, 19), FLNC (1.1%, 14), and DNAJB6 (0.8%, 10). Different sizes of copy number variants including single exon, multi-exon, and whole genes were identified in 7.5% (95) cases in genes including DMD, EMD, CAPN3, ANO5, SGCG, COL6A2, DOK7, and LAMA2. "The Lantern Focused Neuromuscular Panel" enables identification of LGMD subtypes and other myopathies with overlapping clinical features. Prevalence of some MD subtypes was higher than previously reported. Widespread deployment of this comprehensive NGS panel has the potential to ensure early, accurate diagnosis as well as re-define MD epidemiology.

Retinal Vascular Disease in Limb-Girdle Muscular Dystrophy.

To report bilateral retinal vascular occlusive disease in limb-girdle muscular dystrophy. Case report. A 34-year-old Asian woman was referred for evaluation and management of central retinal vein occlusion. Ultra-wide-field fluorescein angiography showed resolving initial peripheral retinal vein occlusion in one eye and peripheral venular segmental staining in the fellow asymmetric eye. Genetic testing established the diagnosis of limb-girdle muscular dystrophy (LGMD). Similar to other forms of muscular dystrophy, LGMD is caused by genetic abnormalities in sarcolemma proteins, a key structural component that connects the intracellular cytoskeleton of a myofiber to the extracellular matrix. Like other muscular dystrophies, LGMD may be associated with retinal vascular abnormalities noted. In this case, retinal vascular smooth muscle dysfunction was seen in LGMD, analogous to reported vascular abnormalities in other muscular dystrophies such as facioscapulohumeral dystrophy and Duchenne muscular dystrophy.

Patient reported quality of life in limb girdle muscular dystrophy

This study determined the frequency and impact of symptoms on quality of life in patients diagnosed with limb girdle muscular dystrophy (LGMD). Participants with a diagnosis of LGMD in registries based at the Coalition to Cure Calpain-3, the Jain foundation, and the Global FKRP Registry competed a survey to report the frequency and relative impact of themes and symptoms of LGMD. Frequency, mean impact, and population impact scores were calculated, and responses were categorized by age, symptom duration, gender, employment status, use of assistive devices, and LGMD subtypes. 134 participants completed the survey. The most prevalent themes included an inability to do activities (100%), limitation with mobility (99.3%), and lower extremity weakness (97.0%). Themes with the greatest impact were: limitations with mobility, lower extremity weakness, and an inability to do activities. Symptom duration and the use of assistive devices were associated with the presence of multiple themes. Employment was associated with the impact of several themes with no differences in frequency. The prevalence and impact of these themes vary in the LMGD population. The most prevalent and impactful themes were related to weakness, but additional concerns related to emotional challenges should also be considered in clinical and research settings.

Disease Progression and Mutation Pattern in a Large Cohort of LGMD R1/LGMD 2A Patients from India.

Calpainopathy is caused by mutations in the CAPN3 . There is only one clinical and genetic study of CAPN3 from India and none from South India. A total of 72 (male[M]:female [F] = 34:38) genetically confirmed probands from 72 independent families are included in this study. Consanguinity was present in 54.2%. The mean age of onset and duration of symptoms are 13.5 ± 6.4 and 6.3 ± 4.7 years, respectively. Positive family history occurred in 23.3%. The predominant initial symptoms were proximal lower limb weakness (52.1%) and toe walking (20.5%). At presentation, 97.2% had hip girdle weakness, 69.4% had scapular winging, and 58.3% had contractures. Follow-up was available in 76.4%, and 92.7% were ambulant at a mean age of 23.7 ± 7.6 years and duration of 4.5 years, remaining 7.3% became wheelchair-bound at 25.5 ± 5.7 years of age (mean duration = 13.5 ± 4.6), 4.1% were aged more than 40 years (duration range = 5–20). The majority remained ambulant 10 years after disease onset. Next-generation sequencing (NGS) detected 47 unique CAPN3 variants in 72 patients, out of which 19 are novel. Missense variants were most common occurring in 59.7% (homozygous = 29; Compound heterozygous = 14). In the remaining 29 patients (40.3%), at least one suspected loss of function variant was present. Common recurrent variants were c.2051–1G > T and c.2338G > C in 9.7%, c.1343G > A, c.802–9G > A, and c.1319G > A in 6.9% and c.1963delC in 5.5% of population. Large deletions were observed in 4.2%. Exon 10 mutations accounted for 12 patients (16.7%). Our study highlights the efficiency of NGS technology in screening and molecular diagnosis of limb-girdle muscular dystrophy with recessive form (LGMDR1) patients in India.

Self-reported physical activity in people with limb-girdle muscular dystrophy and Charcot-Marie-Tooth disease in Norway

BackgroundPhysical activity is associated with positive health effects, but individuals with neuromuscular disease (NMD) may experience constraints being physically active. There is a gap in the literature on the activity level of people with NMDs, and therefore we did a study to determine the physical activity level in people with Limb-Girdle muscular dystrophy (LGMD) and Charcot-Marie-Tooth disease (CMT).MethodsThis study used a cross-sectional design to obtain self-reported physical activity and sitting time among individuals with LGMD and CMT who were recruited from the Norwegian registry for hereditary and congenital neuromuscular diseases.ResultsA total of 127 respondents who filled out questionnaires about either physical activity or sitting time were included in the analysis. Seventy (55.1%) had a diagnosis of CMT and 57 (44.9%) had a diagnosis of LGMD. Seventy-three (57.5%) respondents were female and 54 (42.5%) were male. Among the 108 respondents with available physical activity data, 44.4% reported being physically inactive. Among the 109 respondents with available sitting time data, the average sitting time was 8.6 h. Longer sitting time was associated with higher physical inactivity.ConclusionAmong people with LGMD and CMT in our study, 55.6% reported being physically active. Respondents with LGMD and CMT reported longer sitting time and less physical activity compared with healthy respondents in other studies. Further research should explore variables and measures that can promote physical activity among people with neuromuscular conditions.

Multi-Gene Panel Analysis in the Primary Diagnosis of Limb-Girdle Muscular Dystrophy

Multi-Gene Panel Analysis in the Primary Diagnosis of Limb-Girdle Muscular Dystrophy

Neuromuscular disease. Diagnosis and discovery in limb-girdle muscular dystrophy.

Whole-exome sequencing is a new tool for neuromuscular clinicians, and recent findings show that it improves the diagnosis of limb-girdle muscular dystrophy. The technique has a dual role as a tool for diagnosis and discovery in genetically heterogeneous neuromuscular diseases.

Use of Whole-Exome Sequencing for Diagnosis of Limb-Girdle Muscular Dystrophy

To our knowledge, the efficacy of transferring next-generation sequencing from a research setting to neuromuscular clinics has never been evaluated. To translate whole-exome sequencing (WES) to clinical practice for the genetic diagnosis of a large cohort of patients with limb-girdle muscular dystrophy (LGMD) for whom protein-based analyses and targeted Sanger sequencing failed to identify the genetic cause of their disorder. We performed WES on 60 families with LGMDs (100 exomes). Data analysis was performed between January 6 and December 19, 2014, using the xBrowse bioinformatics interface (Broad Institute). Patients with LGMD were ascertained retrospectively through the Institute for Neuroscience and Muscle Research Biospecimen Bank between 2006 and 2014. Enrolled patients had been extensively investigated via protein studies and candidate gene sequencing and remained undiagnosed. Patients presented with more than 2 years of muscle weakness and with dystrophic or myopathic changes present in muscle biopsy specimens. The diagnostic rate of LGMD in Australia and the relative frequencies of the different LGMD subtypes. Our central goals were to improve the genetic diagnosis of LGMD, investigate whether the WES platform provides adequate coverage of known LGMD-related genes, and identify new LGMD-related genes. With WES, we identified likely pathogenic mutations in known myopathy genes for 27 of 60 families. Twelve families had mutations in known LGMD-related genes. However, 15 families had variants in disease-related genes not typically associated with LGMD, highlighting the clinical overlap between LGMD and other myopathies. Common causes of phenotypic overlap were due to mutations in congenital muscular dystrophy-related genes (4 families) and collagen myopathy-related genes (4 families). Less common myopathies included metabolic myopathy (2 families), congenital myasthenic syndrome (DOK7), congenital myopathy (ACTA1), tubular aggregate myopathy (STIM1), myofibrillar myopathy (FLNC), and mutation of CHD7, usually associated with the CHARGE syndrome. Inclusion of family members increased the diagnostic efficacy of WES, with a diagnostic rate of 60% for "trios" (an affected proband with both parents) vs 40% for single probands. A follow-up screening of patients whose conditions were undiagnosed on a targeted neuromuscular disease-related gene panel did not improve our diagnostic yield. With WES, we achieved a diagnostic success rate of 45.0% in our difficult-to-diagnose cohort of patients with LGMD. We expand the clinical phenotypes associated with known myopathy genes, and we stress the importance of accurate clinical examination and histopathological results for interpretation of WES, with many diagnoses requiring follow-up review and ancillary investigations of biopsy specimens or serum samples.

Clinical Reasoning: A 52-year-old woman with progressive proximal weakness

A 52-year-old woman presented with a 12-year history of progressive limb weakness. She first had trouble climbing stairs and later difficulty getting up from a chair. She also experienced hip and shoulder pain. Over the previous 2 years, combing her hair became difficult. She denied any eyelid drooping, double vision, chewing or swallowing difficulty, slurred speech, shortness of breath, numbness, tingling, autonomic symptoms, or cognitive problems. She did not have any rashes or joint pain. She had no other medical problems and was not taking any medications. She was born full-term and had normal developmental milestones. She was able to keep up with her peers and was a good runner during her childhood. The patient was of German descent and her father and paternal uncle developed leg weakness in their early 40s and were diagnosed with limb-girdle muscular dystrophy (LGMD). They died in a plane crash in their late 40s. The patient's older brother and her uncle's son developed leg weakness in their early 40s and were also diagnosed with LGMD. Both died in their mid-to-late 50s due to respiratory failure. Her brother also had peripheral neuropathy. The diagnosis of LGMD in all family members is based on clinical presentations and muscle biopsies. Genetic studies were not performed. There was no family history of dementia, bone disorder, or motor neuron disease. Her neurologic examination revealed symmetrical weakness of shoulder and hip girdle muscles (Medical Research Council [MRC] grade 4), as well as anterior leg compartment muscles (MRC grade 4+). She also had scapular winging bilaterally. There was no myotonia, muscle rippling, fasciculation, muscle atrophy, or hypertrophy. Deep tendon reflexes were normal except for absent ankle reflexes on both sides. Cognition, cranial nerves, sensory examination, and coordination were normal. She had high-arched feet and hammertoes. There was neither joint contracture nor spinal rigidity.

Elevated Liver Enzymes Indicating a Diagnosis of Limb-Girdle Muscular Dystrophy

A 27-year-old man presented to an internal medicine clinic to establish primary care. His past medical history was significant for elevated liver transaminases found during laboratory monitoring while taking isotretinoin for acne. He had an extensive workup spanning 7 years including serial hepatic function panels after withholding isotretinoin, viral serologies, and two liver biopsies, which eventually led to a diagnosis of an idiopathic elevation in serum transaminases. During his present evaluation, he endorsed complaints of significant muscle soreness with strenuous activity despite conditioning. Creatine kinase was found to be elevated at 11,778 U/l. Nerve conduction studies and electromyogram indicated a myopathy. DNA sequencing confirmed a diagnosis of limb-girdle muscular dystrophy. The aminotransferases are most notable for their association with liver pathology; however, they are also present in other tissues such as heart, kidney, and skeletal muscle. Muscle pathology, including the inherited muscular dystrophies, are often identified by elevations in creatine kinase, but can also be suggested by elevations of aminotransferases. This case illustrates that myopathies should be considered in patients with otherwise unexplained elevations in liver aminotransferases.

Immunohistochemical analysis of calpain 3: Advantages and limitations in diagnosing LGMD2A

Immunoblot is currently the preferred laboratory test to assist the diagnosis of limb-girdle muscular dystrophy (LGMD) 2A (calpainopathy). To assess whether immunohistochemistry may offer a reliable alternative screening we used two antibodies, Calp3–2C4 (exon 1) and Calp3–12A2 (exon 8), to label blots and sections of skeletal muscle from controls and patients with LGMD2A and other muscle diseases. In LGMD2A muscle biopsies a high degree of concordance was found with Calp3–2C4: labelling on sections was absent in patients with no bands on immunoblot and detected in those where CAPN3 bands were seen. Calp3–12A2 results were less consistent, with most samples retaining labelling. Interestingly, CAPN3 was found in all muscle sections from disease control patients irrespective of its detection on immunoblot. Our results show that immunohistochemistry with Calp3–2C4 has a similar pickup rate of LGMD2A as immunoblot and it may therefore be useful for distinguishing the majority of genuine CAPN3 defects from secondary protein reduction. However immunoblot is still needed when CAPN3 is present on sections to show secondary CAPN3 reduction and to identify LGMD2A with variable reduction of CAPN3 bands.

Common mutations detected for diagnosis of limb-girdle muscular dystrophy

Common mutations detected for diagnosis of limb-girdle muscular dystrophy

Limb girdle muscular dystrophies: The clinicopathological viewpoint

Limb girdle muscular dystrophies (LGMD) are characterized by involvement of the pelvic and shoulder girdles, classically with an onset in the second or third decade and a slow progression as opposed to Duchenne muscular dystrophy. In fact, there are many clinical variants that are related to this broad definition. For the past 13 years and since the discovery of calpain-3 as the underlying defect in LGMD 2A in 1995, a number of different genes have been found to cause LGMD; some of whose encoding proteins are located either in the sarcolemma, nucleus, cytosol or in the extra-cellular matrix. Very little is known regarding a possible common pathogenesis between all these entities. The current nomenclature of LGMDs, although a bit confusing, is still necessary to continue the establishment of homogeneous cohorts of patients and to look for unknown genes. The diagnosis of LGMD is nowadays based on a complementary clinical, immunocytochemical and genetic approach that is best achieved in specialized myology centers. In this context, India can make a significant contribution to improve the routine diagnosis in LGMD patients and to find new LGMD genes in genetic isolates. Therapeutic prospects in LGMD, although quite exciting, remain at a preliminary stage, especially those with<br>gene-therapy orientation.

Alpha-sarcoglycanopathy previously misdiagnosed as Duchenne muscular dystrophy: implications for current diagnostics and patient care

Differential diagnosis of limb-girdle muscular dystrophy, including alpha-sarcoglycanopathy and Duchenne muscular dystrophy, is impossible to acheive on clinical grounds alone; therefore immunohistology, Western blotting and molecular genetic analysis are manadatory for a correct diagnosis. The patient's genotype with a hitherto unknown mutation (Tyr134STOP) in exon 5 adds to the growing spectrum of mutations in the alpha-sarcoglycan gene.

Laminin α2-chain gene mutations in two siblings presenting with limb-girdle muscular dystrophy

We report two siblings, an 11-year-old boy and his 7-year-old sister, referred to us with a diagnosis of muscular dystrophy. The boy presented at 22 months with delay in walking. A very high serum creatine kinase (CK) level and a dystrophic muscle biopsy lead to a diagnosis of Duchenne muscular dystrophy prior to the identification of the dystrophin gene. Two years later his sister presented with similar problems. A diagnosis of limb-girdle muscular dystrophy was made when they were shown to have inherited different X-chromosomes and normal expression of dystrophin and all sarcoglycans. Their conditions remained static. Recently a slowing of the peripheral motor nerve conduction velocities and T2-weighted brain magnetic resonance imaging showed increased signal of the white matter, both of which are features of merosin-deficient congenital muscular dystrophy. Immunolabelling using a C-terminal laminin α2 chain antibody showed a reduction in expression, while labelling with another antibody that recognises a 300-kDa fragment showed a very significant reduction. Mutational analysis of the LAMA2 gene showed two mutations: one was a G→C point mutation at position −1 of intron 28 acceptor splicing site. This mutation induced activation of a cryptic splice at nucleotide 4429 of exon 29 and partial skipping of this exon, with conservation of the open reading frame. The other was a nonsense mutation due to a C_T transition at position 5525 of the cDNA sequence (exon 37), resulting in a stop codon. These data confirm that mutations of the LAMA2 gene that do not completely disrupt the production of the protein can give rise to phenotypes considerably milder than classical merosin-deficient congenital muscular dystrophy. Partial laminin α2 deficiency should be considered in the differential diagnosis of limb-girdle muscular dystrophy.

Dystrophin in Limb-Girdle Dystrophy

Dystrophin content in muscle was analyzed by both immunofluorescence and immunoblot in 41 patients with a clinical diagnosis of limb-girdle muscular dystrophy seen at the National Institute of Neuroscience, Tokyo, Japan over a 12-year period.

The frequency of patients with dystrophin abnormalities in a limb‐girdle patient population

Of the 3,048 diagnostic muscle biopsies processed by the National Institute of Neuroscience, Tokyo, over 12 years, 41 cases carried the clinical diagnosis of limb-girdle muscular dystrophy. We have analyzed all 41 cases for dystrophin content in muscle by both immunofluorescence and immunoblot. We identified five male patients with an abnormal dystrophin pattern diagnostic of Becker muscular dystrophy, and two female patients with dystrophin patterns consistent with a manifesting carrier of Duchenne muscular dystrophy diagnosis. Thus, 17% of our limb-girdle patients showed a dystrophinopathy, indicating that they in fact had a disorder related to Duchenne/Becker muscular dystrophy. Misclassification of isolated male limb-girdle patients was 31% (4/13), while misclassification of isolated female limb-girdle patients was 13% (2/15). Using multiplex polymerase chain reaction analyses of small amounts of muscle biopsy DNA confirmed a dystrophin gene deletion in all five male Becker dystrophy patients identified. This study emphasizes the clinical overlap between limb-girdle muscular dystrophy and dystrophinopathies, and reinforces the necessity of dystrophin protein and gene studies for the accurate clinical diagnosis of isolated cases of muscular dystrophy.

Differential diagnosis of limb-girdle muscular dystrophy and spinal muscular atrophy.

Neuromuscular biopsies from 18 patients with proximal muscle weakness were classified electromyographically as myopathy (11 cases), denervation (3 cases), or inconclusive (4 cases). Myopathic changes of muscle fibers occurred in all biopsies. Small angular dark fibers were observed in nine biopsies, and small-group atrophy in four biopsies from the three above-mentioned groups. Two biopsies classified as denervation showed large-group atrophy. Terminal innervation ratio (TIR) was increased only in the three cases classified as denervation and in one inconclusive case. TIR, which is more closely correlated with electromyographic (EMG) results than are muscle fiber changes, may help differentiate spinal muscular atrophy from limb-girdle muscular dystrophy.