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Merosin-deficient congenital muscular dystrophy type 1a: detection of LAMA2 variants in Vietnamese patients.

ABSTRACT: Background: Merosin-deficient congenital muscular dystrophy type 1A (MDC1A), also known as laminin-α2 chain-deficient congenital muscular dystrophy (LAMA2-MD), is an autosomal recessive disease caused by biallelic variants in the LAMA2 gene. In MDC1A, laminin- α2 chain expression is absent or significantly reduced, leading to some early-onset clinical symptoms including severe hypotonia, muscle weakness, skeletal deformity, non-ambulation, and respiratory insufficiency. Methods: Six patients from five unrelated Vietnamese families presenting with congenital muscular dystrophy were investigated. Targeted sequencing was performed in the five probands. Sanger sequencing was carried out in their families. Multiplex ligation-dependent probe amplification was performed in one family to examine an exon deletion. Results: Seven variants of the LAMA2 (NM_000426) gene were identified and classified as pathogenic/likely pathogenic variants using American College of Medical Genetics and Genomics criteria. Two of these variants were not reported in the literature, including c.7156-5_7157delinsT and c.8974_8975insTGAT. Sanger sequencing indicated their parents as carriers. The mothers of family 4 and family 5 were pregnant and a prenatal testing was performed. The results showed that the fetus of the family 4 only carries c.4717 + 5G>A in the heterozygous form, while the fetus of the family 5 carries compound heterozygous variants, including a deletion of exon 3 and c.4644C>A. Conclusion: Our findings not only identified the underlying genetic etiology for the patients, but also provided genetic counseling for the parents whenever they have an offspring.

SUBMITTER: Tran VK

PROVIDER: S-EPMC10301838 | biostudies-literature | 2023

REPOSITORIES: biostudies-literature

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Merosin-deficient congenital muscular dystrophy type 1a: detection of LAMA2 variants in Vietnamese patients.

Tran Van Khanh VK Nguyen Ngoc-Lan NL Tran Lan Ngoc Thi LNT Le Phuong Thi PT Tran Anh Hai AH Pham Tuan L A TLA Lien Nguyen Thi Kim NTK Xuan Nguyen Thi NT Thanh Le Tat LT Ta Thanh Van TV Tran Thinh Huy TH Nguyen Huy-Hoang HH

Frontiers in genetics 20230614

Background: Merosin-deficient congenital muscular dystrophy type 1A (MDC1A), also known as laminin-α2 chain-deficient congenital muscular dystrophy (LAMA2-MD), is an autosomal recessive disease caused by biallelic variants in the LAMA2 gene. In MDC1A, laminin- α2 chain expression is absent or significantly reduced, leading to some early-onset clinical symptoms including severe hypotonia, muscle weakness, skeletal deformity, non-ambulation, and respiratory insufficiency. M ...[more]

PMID: 37388928

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Project description:Merosin-deficient congenital muscular dystrophy (MDC1A) is an autosomal recessive disorder caused by mutations in the LAMA2 gene, resulting in a defective form of the extracellular matrix protein laminin-α2 (LAMA2). Individuals diagnosed with MDC1A exhibit progressive muscle wasting and declining neuromuscular functions. No treatments for this disorder are currently available. We previously showed that postnatal Lama1 upregulation, achieved through CRISPR activation (CRISPRa), compensates for Lama2 deficiency and prevents neuromuscular pathophysiology in a mouse model of MDC1A. In this study, we assessed the feasibility of upregulating human LAMA1 as a potential therapeutic strategy for individuals with MDC1A, regardless of their mutations. We hypothesized that CRISPRa-mediated upregulation of human LAMA1 would compensate for the lack of LAMA2 and rescue cellular abnormalities in MDC1A fibroblasts. Global transcriptomic and pathway enrichment analyses of fibroblasts collected from individuals carrying pathogenic LAMA2 mutations, compared with healthy controls, indicated higher expression of transcripts encoding proteins that contribute to wound healing, including Transforming Growth Factor-β (TGF-β) and Fibroblast Growth Factor (FGF). These findings were supported by wound-healing assays indicating that MDC1A fibroblasts migrated significantly more rapidly than the controls. Subsequently, we treated the MDC1A fibroblasts with SadCas9-2XVP64 and sgRNAs targeting the LAMA1 promoter. We observed robust LAMA1 expression, which was accompanied by significant decreases in cell migration and expression of FGFR2, TGF-β2, and ACTA2, which are involved in the wound-healing mechanism in MDC1A fibroblasts. Collectively, our data suggest that CRISPRa-mediated LAMA1 upregulation may be a feasible mutation-independent therapeutic approach for MDC1A. This strategy might be adapted to address other neuromuscular diseases and inherited conditions in which strong compensatory mechanisms have been identified.

Project description:LAMA2-deficient congenital muscular dystrophy (LAMA2-CMD) is a severe neuromuscular disorder caused by LAMA2 mutations, leading to muscle degeneration, chronic inflammation, and fibrosis. Histopathological assessment of muscle biopsies from LAMA2-CMD patients and mouse models show clear evidence of inflammation, which oftentimes are regarded as one of the typical dystrophic hallmarks. However, the composition of immune cells in the laminin-deficient muscles remain understood. Consequently, targeted pharmacological intervention to reduce inflammation has never been tested. In this study, we characterized the immune landscape in dyW mouse model of LAMA2-CMD using RNA sequencing and flow cytometry. Transcriptomic analysis of dyW quadriceps identified 2,143 differentially expressed genes, with most of the upregulated genes belong to immune-related pathways. Lgals3 (Galectin-3) was significantly upregulated (log₂FC = 4.27, FDR p-value= 9.21x10-88) and identified as a key upstream regulator of the immune-related pathways. In parallel, flow cytometry analysis revealed elevated leukocyte (CD45⁺) infiltration, with macrophages as the predominant cell population. Pro-inflammatory (M1) macrophages were increased, whereas anti-inflammatory (M2) macrophages remained low, indicating persistent inflammation and impaired resolution. Interestingly, Galectin-3+ macrophages were significantly enriched, which strongly suggest that Galectin-3 drives inflammation in LAMA2-CMD. Treatment of dyW mice with TD-139, a Galectin-3 inhibitor, reduced leukocyte infiltration, decreased Galectin-3+ macrophages, and shifted macrophage polarization toward an M2 anti-inflammatory profile. In addition, RNA sequencing of TD-139-treated dyW muscles showed upregulation of muscle repair pathways and downregulation of fibrosis-related genes. These findings establish Galectin-3-expressing macrophages as an important player in LAMA2-CMD pathophysiology. Importantly, it warrants further investigation on the therapeutic potential of TD-139-mediated inhibition of Galectin-3, including long-term preclinical study, in LAMA2-CMD and potentially other dystrophic conditions driven by chronic immune activation.

Dataset Information

Merosin-deficient congenital muscular dystrophy type 1a: detection of LAMA2 variants in Vietnamese patients.

Publications

Merosin-deficient congenital muscular dystrophy type 1a: detection of <i>LAMA2</i> variants in Vietnamese patients.

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