LAMA2 gene analysis in a cohort of 26 congenital muscular dystrophy patients

Congenital muscular dystrophy type 1A (MDC1A) is caused by mutations in the LAMA2 gene encoding laminin-alpha2. We describe the molecular study of 26 patients with clinical presentation, magnetic resonance imaging and/or laminin-alpha2 expression in muscle, compatible with MDC1A. The combination of full genomic sequencing and complementary DNA analysis led to the particularly high mutation detection rate of 96% (50/52 disease alleles). Besides 22 undocumented polymorphisms, 18 different mutations were identified in the course of this work, 14 of which were novel. In particular, we describe the first fully characterized gross deletion in the LAMA2 gene, encompassing exon 56 (c.7750-1713_7899-2153del), detected in 31% of the patients. The only two missense mutations detected were found in heterozygosity with nonsense or truncating mutations in the two patients with the milder clinical presentation and a partial reduction in muscle laminin-alpha2. Our results corroborate the previous few genotype/phenotype correlations in MDC1A and illustrate the importance of screening for gross rearrangements in the LAMA2 gene, which may be underestimated in the literature.     

Cardiomyopathy in patients with POMT1-related congenital and limb-girdle muscular dystrophy

Protein-o-mannosyl transferase 1 (POMT1) is a glycosyltransferase involved in α-dystroglycan (α-DG) glycosylation. Clinical phenotype in POMT1-mutated patients ranges from congenital muscular dystrophy (CMD) with structural brain abnormalities, to limb-girdle muscular dystrophy (LGMD) with microcephaly and mental retardation, to mild LGMD. No cardiac involvement has until now been reported in POMT1-mutated patients. We report three patients who harbored compound heterozygous POMT1 mutations and showed left ventricular (LV) dilation and/or decrease in myocardial contractile force: two had a LGMD phenotype with a normal or close-to-normal cognitive profile and one had CMD with mental retardation and normal brain MRI. Reduced or absent α-DG immunolabeling in muscle biopsies were identified in all three patients. Bioinformatic tools were used to study the potential effect of POMT1-detected mutations. All the detected POMT1 mutations were predicted in silico to interfere with protein folding and/or glycosyltransferase function. The report on the patients described here has widened the clinical spectrum associated with POMT1 mutations to include cardiomyopathy. The functional impact of known and novel POMT1 mutations was predicted with a bioinformatics approach, and results were compared with previous in vitro studies of protein-o-mannosylase function.     

Clinical and molecular study in congenital muscular dystrophy with partial laminin alpha 2 (LAMA2) deficiency

Complete laminin alpha2 (LAMA2) deficiency causes approximately half of congenital muscular dystrophy (CMD) cases. Many loss-of-function mutations have been reported in these severe, neonatal-onset patients, but only single missense mutations have been found in milder CMD with partial laminin alpha2 deficiency. Here, we studied nine patients diagnosed with CMD who showed abnormal white-matter signal at brain MRI and partial deficiency of laminin alpha2 on immunofluorescence of muscle biopsy. We screened the entire 9.5 kb laminin alpha2 mRNA from patient muscle biopsy by direct capillary automated sequencing, single strand conformational polymorphism (SSCP), or denaturing high performance liquid chromatography (DHPLC) of overlapping RT-PCR products followed by direct sequencing of heteroduplexes. We identified laminin alpha2 sequence changes in six of nine CMD patients. Each of the gene changes identified, except one, was novel, including three missense changes and two splice-site mutations. The finding of partial laminin alpha2 deficiency by immunostaining is not specific for laminin alpha2 gene mutation carriers, with only two patients (22%) showing clear causative mutations, and an additional three patients (33%) showing possible mutations. The clinical presentation and disease progression was homogeneous in the laminin alpha2-mutation positive and negative CMD patients.     

Identification of lamin A/C ( LMNA) gene mutations in Korean patients with autosomal dominant Emery-Dreifuss muscular dystrophy and limb-girdle muscular dystrophy 1B

Mutations in the LMNA gene encoding lamins A and C by alternative splicing have been found to cause at least four different kinds of genetic disorders: autosomal dominant Emery-Dreifuss muscular dystrophy (EDMD2; MIM 181350); limb-girdle muscular dystrophy type 1B (LGMD1B; MIM 159001); dilated cardiomyopathy type 1A (CMD1A; MIM 115200); and familial partial lipodystrophy (FPLD; MIM 151660). Recently, we have studied two Korean patients with atrioventricular conduction defects. They had variable extents of muscular dystrophy; one patient was diagnosed with EDMD2 and the other with LGMD1B. We performed a mutation analysis of the LMNA gene by direct sequencing and found two different missense mutations: R249Q and R377L, in the EDMD2 and LGMD1B patient, respectively. The R249Q mutation is located within the central rod domain of the LMNA gene, and has been described in at least five unrelated sporadic EDMD2 patients. On the other hand, the R377L mutation, also located within the rod domain, is a novel mutation, although a histidine substitution instead of leucine (R377H) has been reported previously in an LGMD1B patient. To our knowledge, this is the first report of LMNA gene mutations in Korean patients with EDMD2 and LGMD1B. Received: November 19, 2001 / Accepted: February 8, 2002     

一个先天性肌营养不良1A型家系的临床、分子病理及遗传学研究

目的 分析并确立1个先天性肌营养不良1A型(congenital muscular dystrophy type 1A,MDC1A)家系的临床、分子病理及遗传学特征.方法 收集该家系患儿及父母的临床资料,对患儿进行腓肠肌活检,采用特异抗体行免疫组织化学染色,包括merosin抗体、抗α抗肌萎缩相关糖蛋白(α-dystroglycan,α-DG)糖链抗体ⅡH6、抗β抗肌萎缩相关糖蛋白(β-dystroglycan,β-DG)抗体及抗肌萎缩蛋白(dystrophin)C末端(Dys-C)抗体;提取患儿及其父母外周血基因组DNA,PCR扩增LAMA2基因的65个外显子,以琼脂糖凝胶电泳鉴定PCR产物,PCR产物纯化后DNA直接测序,确定基因突变的类型,分析基因型和表型的关系.结果 患儿自幼运动发育落后,肌病面容,肌酶中度升高,头颅MRI提示脑白质异常信号,临床诊断为先天性肌营养不良1A型.通过活检肌肉组织免疫学染色提示merosin完全缺失,dystrophin和DG表达正常.基因检测显示先证者LAMA2基因第5外显子c.817A>T纯合突变,其父母分别为此位点杂合突变.结论 本次研究进一步明确了MDC1A患儿的临床特点,通过分子遗传学分析发现该患儿为LAMA2基因c.817A>T(p.R273X)纯合无义突变,其突变基因分别来自父母,符合先天性肌营养不良1A型常染色体隐性遗传的规律,可确诊为先天性肌营养不良1A型.     

Impairment of p38 MAPK-mediated cytosolic phospholipase A2 activation in the kidneys is associated with pathogenicity of Candida albicans

In studying the mechanisms underlying the susceptibility of the kidney to candidal infection, we previously reported that the reduced production of cytokines [i.e. tumour necrosis factor-alpha (TNF-alpha)] via platelet-activating factor (PAF)-induced activation of nuclear factor-kappaB (NF-kappaB) renders the organ susceptible to the fungal burden. In this study, we investigated the possibility that pathogenic Candida albicans may evade clearance and perhaps even multiply by inhibiting elements in the signalling pathway that lead to the production of TNF-alpha. The fungal burden of pathogenic C. albicans in the kidneys was 10(4)-10(5)-fold higher than that of a non-pathogenic strain. PAF-induced early activation of NF-kappaB and TNF-alpha mRNA expression were both observed in the kidneys of mice infected with non-pathogenic strains of C. albicans, but not in mice infected with pathogenic strains. Impairment of PAF-mediated early NF-kappaB activation following infection with pathogenic C. albicans was associated with the prevention of activation of the enzyme cytosolic phospholipase A(2) (cPLA(2)) as well as the upstream pathway of cPLA(2), p38 mitogen-activated protein kinase. Collectively, these findings indicate that C. albicans exerts its pathogenicity through impairing the production of anticandidal cytokines by preventing cPLA(2) activity. This novel mechanism provides insight into understanding pathogenic C. albicans and perhaps identifies a target for its treatment.     

IL-1β promotes cervical cancer through activating NF-κB/CCL-2

Cervical cancer is a malignancy with high morbidity and mortality among women. Interleukin (IL)-1β, chemokine (C-C motif) ligand 2 (CCL-2), and activation of NF-κB have been proven to be closely related to the progression of various tumors. However, their role in cervical cancer remains unclear. Cell proliferation, migration, and invasion were detected using MTT, wound healing, and transwell assays. Western blotting and qRT-PCR were used to measure expression of target genes. IL-1β greatly promoted the release of CCL-2 from HeLa cells. Activation of NF-κB and phosphorylated NF-κB (p65) nuclear translocation were accelerated by IL-1β. TPCA-1, a blocker of NF-κB, significantly inhibited the release of CCL-2 from HeLa cells. TPCA-1 markedly reversed the promotional effect of IL-1β on viability of HeLa cells. IL-1β increased the cell migration, proliferation, and invasion of HeLa cells through targeting the NF-κB/CCL-2 pathway. IL-1β/NF-κB/CCL-2 might be a promising treatment target for cervical cancer treatment and prevention.     

LAMA2 gene mutation update: Toward a more comprehensive picture of the laminin‐α2 variome and its related phenotypes

Congenital muscular dystrophy type 1A (MDC1A) is one of the main subtypes of early‐onset muscle disease, caused by disease‐associated variants in the laminin‐α2 (LAMA2) gene. MDC1A usually presents as a severe neonatal hypotonia and failure to thrive. Muscle weakness compromises normal motor development, leading to the inability to sit unsupported or to walk independently. The phenotype associated with LAMA2 defects has been expanded to include milder and atypical cases, being now collectively known as LAMA2‐related muscular dystrophies (LAMA2‐MD). Through an international multicenter collaborative effort, 61 new LAMA2 disease‐associated variants were identified in 86 patients, representing the largest number of patients and new disease‐causing variants in a single report. The collaborative variant collection was supported by the LOVD‐powered LAMA2 gene variant database ( https://www.LOVD.nl/LAMA2 ), updated as part of this work. As of December 2017, the database contains 486 unique LAMA2 variants (309 disease‐associated), obtained from direct submissions and literature reports. Database content was systematically reviewed and further insights concerning LAMA2‐MD are presented. We focus on the impact of missense changes, especially the c.2461A > C (p.Thr821Pro) variant and its association with late‐onset LAMA2‐MD. Finally, we report diagnostically challenging cases, highlighting the relevance of modern genetic analysis in the characterization of clinically heterogeneous muscle diseases.     

CLEC3B is a novel causative gene for macular-retinal dystrophy

PurposeMacular degeneration is the leading cause of blindness worldwide. In this study, we aimed to define a new subtype of macular-retinal dystrophy and its genetic predisposition in 5 families.MethodsExome sequencing was performed to determine the putative disease-causing genes in patients with inherited macular disorders confirmed through comprehensive ophthalmic examinations. To validate its functional consequence, adeno-associated virus–mediated mutant gene was delivered into the murine retina, and both structural and functional tests were performed to investigate its pathological effects in vivo.ResultsIn total, 5 multigenerational families diagnosed with autosomal dominant maculoretinopathy were found to carry a pathogenic variant in a new gene, CLEC3B, which encodes tetranectin, a plasminogen kringle-4 binding protein. Consistent with the disease phenotypes of patients, mice that received subretinal injections with the CLEC3B variant displayed multiple subretinal hyperreflective deposits, reduced retinal thickness, and decreased electroretinographic responses. Moreover, the optokinetic tracking response indicated that spatial frequency was significantly lower (P < .05), implying impaired visual function in these mice.ConclusionWe have presented a new subtype of macular-retinal dystrophy in 5 families as well as a new pathogenic gene, CLEC3B, providing new insights into maculoretinopathy etiology.     

Severe congenital muscular dystrophy in a Mexican family with a new nonsense mutation (R2578X) in the laminin α-2 gene

 The congenital muscular dystrophies (CMDs) are a heterogeneous group of autosomal recessive disorders. Approximately one half of cases diagnosed with classic CMD show primary deficiency of the laminin α2 chain of merosin. Complete absence of this protein is usually associated with a severe phenotype characterized by drastic muscle weakness and characteristic changes in white matter in cerebral magnetic resonance imaging (MRI). Here we report an 8-month-old Mexican female infant, from a consanguineous family, with classical CMD. Serum creatine kinase was elevated, muscle biopsy showed dystrophic changes, and there were abnormalities in brain MRI. Immunofluorescence analysis demonstrated the complete absence of laminin α2. In contrast, expression of α-, β-, γ-, and δ-sarcoglycans and dystrophin, all components of the dystrophin–glycoprotein complex, appeared normal. A homozygous C  T substitution at position 7781 that generated a stop codon in the G domain of the protein was identified by mutation analysis of the laminin α2 gene (LAMA2). Sequence analysis on available DNA samples of the family showed that parents and other relatives were carriers of the mutation. Received: August 22, 2002 / Accepted: November 11, 2002 Acknowledgments The authors wish to thank Dr. Pascale Guicheney (INSERMU523, Institute de Myologie), who kindly provided us with the primers' sequences and PCR conditions to amplify exons of LAMA2. This work was supported by CONACYT (Mexico) grant 34603-M, and Fondo de Fomento para la Investigacion-IMSS (Mexico) grant FP-0038/764. All DNA sequencing was carried out at the Centro de Instrumentos del Instituto Mexicano del Seguro Social (IMSS), Mexico City. The first two authors contributed equally to this work. Correspondence to:R.M. Coral-Vazquez     

Analysis of DYSF gene mutations in two pedigrees affected with limb-girdle muscular dystrophy type 2BCSCD

Objective: To analyze mutations of DYSF gene in two pedigrees affected with limb-girdle muscular dystrophy 2B (LGMD-2B). Methods: Genomic DNA was extracted from peripheral blood samples of the two probands and unaffected family members. Variant sites were screened by next-generation sequencing using gene panel as well as Sanger sequencing. Results: Four pathogenic mutations of the DYSF gene were detected, which included a de novo mutation and three mutations with uncertain significance. In pedigree 1, the proband carried compound heterozygous mutations of c. 1667T>C (p. Leu556Pro) and c. 5567T>A (p. Vall856Glu), which were respectively inherited from her mother and father. Proband of pedigree 2 carried compound heterozygous mutations of c. 4853A>G (p. Tyrl618Cys) and c. 4876G> A (p. Vall612Ile), among which c. 4876G> A (p. Vall626Ile) was also found in his father and grandfather, while c. 4853A>G (p. Tyrl618Cys) was detected in his mother and grandmother. Conclusion: The two compound heterozygous mutations of the DYSF gene probably underlie the LGMD2B in the two pedigrees. Next generation sequencing has conferred great advantage for gene diagnosis of hereditary myopathy. © 2018 MeDitorial Ltd. All rights reserved.     

LIMS2 mutations are associated with a novel muscular dystrophy,severe cardiomyopathy and triangular tongues

Limb girdle muscular dystrophy (LGMD) is a heterogeneous group of genetic disorders leading to progressive muscle degeneration and often associated with cardiac complications. We present two adult siblings with childhood‐onset of weakness progressing to a severe quadriparesis with the additional features of triangular tongues and biventricular cardiac dysfunction. Whole exome sequencing identified compound heterozygous missense mutations that are predicted to be pathogenic in LIMS2. Biopsy of skeletal muscle demonstrated disrupted immunostaining of LIMS2. This is the first report of mutations in LIMS2 and resulting disruption of the integrin linked kinase (ILK)–LIMS–parvin complex associated with LGMD.     

Aitongxiao improves pain symptoms of rats with cancer pain by reducing IL-1, TNF-α, and PGE2

Objective: To explore the mechanism of Aitongxiao in improving pain symptoms of rats with cancer pain. Methods: Walker 256 breast cancer cells were injected into the right tibial bone marrow cavity of normal female rats to establish a rat model of tibial cancer pain. The rats with successful model replication were randomly divided into normal group (NG), Hank solution group (HSG), cancer pain model group (CPMG), and Aitongxiao+cancer pain model group (ATX+CPMG). The pain response score, mechanical pain hindpaw withdrawal threshold, and latent heat pain of rats were evaluated, and the changes of serum IL-1β, TNF-α, PGE2 and blood cell counts of rats were detected. Results: Compared with the NG, the pain response score was increased, the mechanical pain hindpaw withdrawal threshold and latent heat pain were decreased, and IL-1β, TNF-α, and PGE2 were increased in CPMG. Compared with the CPMG, the pain response score was decreased, the mechanical pain hindpaw withdrawal threshold and latent heat pain were increased, and IL-1β, TNF-α, and PGE2 were decreased in ATX+CPMG. There was no significant change in blood cell count in each group. Conclusion: Aitongxiao can improve the pain symptoms of rats with tibial cancer pain. Its mechanism may be related to the reduction of IL-1β, TNF-α, and PGE2 levels.     

Echinogenic action of L-α-lysophosphatidylcholine in Duchenne muscular dystrophy: A study on carrier detection

The percentage of echinocytes induced after red cell treatment with L-α-lysophosphatidylcholine in the blood of 16 patients affected by Duchenne muscular dystropy (DMD) has been evaluated. Moreover, 15 mothers, 10 sisters, and 15 fathers were also included in the study. We found an increased level of echinocytes in dystrophic patients and in known and possible carriers. Correlations were also evaluated between echinocytes and serum enzymes used in DMD diagnosis, showing an increase of echinocytes also in DMD carriers with normal levels of serum creatine kinase, lactate dehydrogenase, and aldolase. Our results suggest that the sensitivity of erythrocytes to L-α-lysophosphatidylcholine in DMD could be used as a diagnostic test for carrier detection.     

Haemoglobin switching modulator SNPs rs5006884 is associated with increased HbA2 in β-thalassaemia carriers

IntroductionHaemoglobin A₂ (HbA₂), the tetramer of α- and δ-globin chains, is used as a diagnostic biomarker for β-thalassaemia carriers. The HbA₂ levels are regulated by the presence of HPFH, δ-thalassaemia, HbA_1/2 gene triplication, and variants of KLF1, β-globin gene, and HbF regulating QTLs. Saudi Arabia has a high incidence of borderline HbA₂ levels, thereby making it difficult to classify the haemoglobinopathies. This study aims to investigate the association of known HbF enhancer QTL gene SNPs with HbA₂ levelsMaterial and methods14 Specific SNPs in BCL11A, HMIP, OR51B6, HBBP1, and HBG2 loci were genotyped in 164 Saudi β-thalassaemia carriers by TaqMan assay to validate their role as regulators of HbA₂ levels. HbA2 levels were determined using the Variant II β-Thalassemia Short Program Recorder kit. The non-random association of these SNPs was tested using HaploView software. Protein interaction was assessed using 3D structure modelling for OR51B6 (rs5006884), comparative energy minimisation, and root-mean-square deviation (RMSD) prediction.ResultsElevated HbA₂ levels were associated with SNPs in HBBP1, OR51B6, and TCT haplotype from HBG2 promoter region. The bioinformatics modelling and prediction revealed that the exonic rs5006884 had RMSD value deviations and significantly varied binding energy minimisation. α-globin variations were found in 57.92% of individuals but were not associated with elevated HbA₂.ConclusionsThe haemoglobin switching modulators rs2071348, rs7482144, and rs5006884 are involved in regulation of HbA₂ level with rs5006884 influencing the tetramer formation. Screening for haemoglobinopathies should take these SNPs into consideration, specifically in borderline HbA₂ cases. Assiduous analysis of rs5006884 as HbA₂ modulator for amelioration of disease severity is recommended.     

Analysis of MTMR1 expression and correlation with muscle pathological features in juvenile/adult onset myotonic dystrophy type 1 (DM1) and in myotonic dystrophy type 2 (DM2)

Among genes abnormally expressed in myotonic dystrophy type1 (DM1), the myotubularin-related 1 gene (MTMR1) was related to impaired muscle differentiation. Therefore, we analyzed MTMR1 expression in correlation with CUG-binding protein1 (CUG-BP1) and muscleblind-like1 protein (MBNL1) steady-state levels and with morphological features in muscle tissues from DM1 and myotonic dystrophy type 2 (DM2) patients.Semi-quantitative RT-PCR for MTMR1 was done on muscle biopsies and primary muscle cultures. The presence of impaired muscle fiber maturation was evaluated using immunochemistry for neural cell adhesion molecule (NCAM), Vimentin and neonatal myosin heavy chain. CUG-BP1 and MBNL1 steady-state levels were estimated by Western blot. RNA-fluorescence in situ hybridization combined with immunochemistry for CUG-BP1, MBNL1 and NCAM were performed on serial muscle sections.An aberrant splicing of MTMR1 and a significant amount of NCAM-positive myofibers were detected in DM1 and DM2 muscle biopsies; these alterations correlated with DNA repeat expansion size only in DM1. CUG-BP1 levels were increased only in DM1 muscles, while MBNL1 levels were similar among DM1, DM2 and controls. Normal and NCAM-positive myofibers displayed no differences either in the amount of ribonuclear foci and the intracellular distribution of MBNL1 and CUG-BP1.In conclusion, an aberrant MTMR1 expression and signs of altered myofiber maturation were documented in both DM1 and in DM2 muscle tissues. The more severe dysregulation of MTMR1 expression in DM1 versus DM2, along with increased CUG-BP1 levels only in DM1 tissues, suggests that the mutual antagonism between MBNL1 and CUG-BP1 on alternative splicing is more unbalanced in DM1.     

ZPLD1 gene is disrupted in a patient with balanced translocation that exhibits cerebral cavernous malformations

The past few years have seen rapid advances in our understanding of the genetics and molecular biology of cerebral cavernous malformations (CCM) with the identification of the CCM1, CCM2, and CCM3 genes. Recently, we have recruited a patient with an X/3 balanced translocation that exhibits CCM. By fluorescent in situ hybridization analysis, sequence analysis tools and database mining procedures, we refined the critical region to an interval of 200-kb and identified the interrupted ZPLD1 gene. We detected that the mRNA expression level of ZPLD1 gene is consistently decreased 2.5-fold versus control (P=0.0006) with allelic loss of gene expression suggesting that this protein may be part of the complex signaling pathway implicated in CCM formation.