Robust genotyping tool for autosomal recessive type of limb-girdle muscular dystrophies

Prevalence of chronic pain in a national cohort of patients with limb-girdle muscular dystrophy: a cross-sectional study

PURPOSE

The aim was to investigate the prevalence, characteristics, predictors, and consequences of chronic pain in a national cohort of patients with limb-girdle muscular dystrophy (LGMD).

MATERIALS AND METHODS

Questionnaires were sent to all Danish LGMD patients (≥18 years of age) registered with the National Rehabilitation Center for Neuromuscular Diseases.

RESULTS

Of 209 patients, 121 responded. 44.7% of the patients experienced persistent (daily or constant) chronic pain lasting more than 3 months. 21.0% of patients experienced chronic pain that was not daily. Most pain patients experienced three or more pain problems, primarily in the lower back, neck, shoulders, hips, and legs. Symptoms suggestive of neuropathic pain were sometimes present. Patients with persistent chronic pain reported moderate pain interference with daily activities, greater psychological distress, and lower quality of life compared to patients without pain but did not differ regarding physical functioning. Sex, age, LGMD duration, LGMD type, mechanical ventilation use, mobility, arm function, or performance on activities of daily living did not predict chronic pain.

CONCLUSION

Chronic pain is common in patients with LGMD. Chronic pain should be considered an important component of LGMD and addressed in the clinic and rehabilitation setting from a biopsychosocial perspective.Implication for rehabilitationChronic pain is highly prevalent in patients with limb-girdle muscular dystrophy.Health professionals need to systematically ask patients about pain and the influence of pain on everyday life irrespective of LGMD-duration and extent of muscle wastage.Chronic pain and psychological distress need to be addressed in the clinic and rehabilitation setting as an additional disabling component of LGMD and this should be done within a biopsychosocial framework.

Overview of Neuromuscular Disorder Molecular Diagnostic Experience for the Population of Latvia

Background and Objectives

Genetic testing has become an integral part of health care, allowing the confirmation of thousands of hereditary diseases, including neuromuscular disorders (NMDs). The reported average prevalence of individual inherited NMDs is 3.7–4.99 per 10,000. This number varies greatly in the selected populations after applying population-wide studies. The aim of this study was to evaluate the effect of genetic analysis as the first-tier test in patients with NMD and to calculate the disease prevalence and allelic frequencies for reoccurring genetic variants.

Methods

Patients with NMD from Latvia with molecular tests confirming their diagnosis in 2008–2020 were included in this retrospective study.

Results

Diagnosis was confirmed in 153 unique cases of all persons tested. Next-generation sequencing resulted in a detection rate of 37%. Two of the most common childhood-onset NMDs in our population were spinal muscular atrophy and dystrophinopathies, with a birth prevalence of 1.01 per 10,000 newborns and 2.08 per 10,000 (male newborn population), respectively. The calculated point prevalence was 0.079 per 10,000 for facioscapulohumeral muscular dystrophy type 1, 0.078 per 10,000 for limb-girdle muscular dystrophy, 0.073 per 10,000 for nondystrophic congenital myotonia, 0.052 per 10,000 for spinobulbar muscular atrophy, and 0.047 per 10,000 for type 1 myotonic dystrophy.

Discussion

DNA diagnostics is a successful approach. The carrier frequencies of the common CAPN3, FKRP, SPG11, and HINT1 gene variants as well as that of the SMN1 gene exon 7 deletion in the population of Latvia are comparable with data from Europe. The carrier frequency of the CLCN1 gene variant c.2680C>T p.(Arg894Ter) is 2.11%, and consequently, congenital myotonia is the most frequent NMD in our population.

Compound heterozygous DYSF variants causing limb-girdle muscular dystrophy type 2B in a Chinese family

BACKGROUND

The dysferlin gene or the DYSF gene encodes the Ca²⁺ -dependent phospholipid-binding protein dysferlin, which belongs to the ferlin family and is associated with muscle membrane regeneration and repair. Variants in the DYSF gene are responsible for limb-girdle muscular dystrophy type 2B (LGMD2B), also called limb-girdle muscular dystrophy recessive 2 (LGMDR2), a rare subtype of muscular dystrophy involving progressive muscle weakness and atrophy. The present study aimed to identify the variants responsible for the clinical symptoms of a Chinese patient with limb girdle muscular dystrophies (LGMDs) and to explore the genotype-phenotype associations of LGMD2B.

METHODS

A series of clinical examinations, including blood tests, magnetic resonance imaging scans for the lower legs, electromyography and muscle biopsy, was performed on the proband diagnosed with muscular dystrophies. Whole exome sequencing was conducted to detect the causative variants, followed by Sanger sequencing to validate these variants.

RESULTS

We identified two compound heterozygous variants in the DYSF gene, c.1058 T>C, p.(Leu353Pro) in exon 12 and c.1461C>A/p.Cys487* in exon 16 in this proband, which were inherited from the father and mother, respectively. In silico analysis for these variants revealed deleterious results by PolyPhen-2 (Polymorphism Phenotyping v2; http://genetics.bwh.harvard.edu/pph2), SIFT (Sorting Intolerant From Tolerant; https://sift.bii.a-star.edu.sg), PROVEAN (Protein Variation Effect Analyzer; http://provean.jcvi.org/seq_submit.php) and MutationTaster (http://www.mutationtaster.org). In addition, the two compound heterozygous variants in the proband were absent in 100 control individuals who had an identical ethnic origin and were from the same region, suggesting that these variants may be the pathogenic variants responsible for the LGMD2B phenotypes for this proband.

CONCLUSIONS

The present study broadens our understanding of the mutational spectrum of the DYSF gene, which provides a deep insight into the pathogenesis of LGMDs and accelerates the development of a prenatal diagnosis.

Predominance of Dystrophinopathy Genotypes in Mexican Male Patients Presenting as Muscular Dystrophy with A Normal Multiplex Polymerase Chain Reaction DMD Gene Result: A Study Including Targeted Next-Generation Sequencing

The complete mutational spectrum of dystrophinopathies and limb-girdle muscular dystrophy (LGMD) remains unknown in Mexican population. Seventy-two unrelated Mexican male patients (73% of pediatric age) with clinical suspicion of muscular dystrophy and no evidence of DMD gene deletion on multiplex polymerase chain reaction (mPCR) analysis were analyzed by multiplex ligation-dependent probe amplification (MLPA). Those with a normal result were subjected to Sanger sequencing or to next-generation sequencing for DMD plus 10 selected LGMD-related genes. We achieved a diagnostic genotype in 80.5% (n = 58/72) of patients with predominance of dystrophinopathy-linked genotypes (68%, n = 49/72), followed by autosomal recessive LGMD-related genotypes (types 2A-R1, 2C-R5, 2E-R4, 2D-R3 and 2I-R9; 12.5%, n = 9/72). MLPA showed 4.2% of false-negatives for DMD deletions assessed by mPCR. Among the small DMD variants, 96.5% (n = 28/29) corresponded to null-alleles, most of which (72%) were inherited through a carrier mother. The FKRP p.[Leu276Ile]; [Asn463Asp] genotype is reported for the first time in Mexican patients as being associated with dilated cardiomyopathy. Absence of dysferlinopathies could be related to the small sample size and/or the predominantly pediatric age of patients. The employed strategy seems to be an affordable diagnosis approach for Mexican muscular dystrophy male patients and their families.

Prevalence, pathological mechanisms, and genetic basis of limb-girdle muscular dystrophies: A review

Limb-girdle muscular dystrophies (LGMDs) are a highly heterogeneous group of neuromuscular disorders that are associated with weakness and wasting of muscles in legs and arms. Signs and symptoms may begin at any age and usually worsen by time. LGMDs are autosomal disorders with different types and their prevalence is not the same in different areas. New technologies such as next-generation sequencing can accelerate their diagnosis. Several important pathological mechanisms that are involved in the pathology of the LGMD include abnormalities in dystrophin-glycoprotein complex, the sarcomere, glycosylation of dystroglycan, vesicle and molecular trafficking, signal transduction pathways, and nuclear functions. Here, we provide a comprehensive review that integrates LGMD clinical manifestations, prevalence, and some pathological mechanisms involved in LGMDs.