Biomedical subjects

Miriam Carl

Publications and source records attributed to Miriam Carl.

3 recordsLinked to original sources

PubMed2006

Painful enlargement of the calf muscles in limb girdle muscular dystrophy type 2B (LGMD2B) with a novel compound heterozygous mutation in DYSF.

Limb girdle muscular dystrophy type 2B (LGMD2B) and Miyoshi Myopathy are caused by mutations in the dysferlin gene. The phenotype of these allelic disease variants can vary considerably. We report on an adolescent female with a severe and rapidly progressing clinical course of LGMD2B which has been suggested by the muscle histopathology and Western blot and proven by mutation analysis in the Dysferlin gene. We detected a novel compound heterozygous mutation of which one affects the extracellular part of the protein. This is the first report on a mutation in this region of dysferlin and might explain the unusual phenotype of the patient.

Adolescent↗

PubMed2006

Novel sequence variants in dysferlin-deficient muscular dystrophy leading to mRNA decay and possible C2-domain misfolding.

Mutations in the gene encoding dysferlin (DYSF) cause the allelic autosomal recessive disorders limb girdle muscular dystrophy 2B and Miyoshi myopathy. It encompasses 55 exons spanning 150 kb of genomic DNA. Dysferlin is involved in membrane repair in skeletal muscle. We identified three families with novel sequence variants in DYSF. All affected family members showed limb girdle weakness and had reduced or absent dysferlin protein on immunohistochemistry. All exons of DYSF were screened by genomic sequencing. Five novel variants in DYSF were found: two missense mutations (c.895G>A and c.4022T>C), one 5' donor splice-site variant (c.855+1delG), one nonsense mutation (c.1448C>A), and a variant in the 3'UTR of DYSF (c.*107T>A). All alterations were confirmed by restriction enzyme analysis and not found in 400 control alleles. Nonsense mediated RNA decay or changes in the three-dimensional protein structure resulting in intracellular dysferlin aggregates and finally the lack of dysferlin protein were identified as consequences of the novel DYSF variants.

Adult↗

PubMed2005

Increased susceptibility to complement attack due to down-regulation of decay-accelerating factor/CD55 in dysferlin-deficient muscular dystrophy.

Dysferlin is expressed in skeletal and cardiac muscles. However, dysferlin deficiency results in skeletal muscle weakness, but spares the heart. We compared intraindividual mRNA expression profiles of cardiac and skeletal muscle in dysferlin-deficient SJL/J mice and found down-regulation of the complement inhibitor, decay-accelerating factor/CD55, in skeletal muscle only. This finding was confirmed on mRNA and protein levels in two additional dysferlin-deficient mouse strains, A/J mice and Dysf-/- mice, as well as in patients with dysferlin-deficient muscular dystrophy. In vitro, the absence of CD55 led to an increased susceptibility of human myotubes to complement attack. Evidence is provided that decay-accelerating factor/CD55 is regulated via the myostatin-SMAD pathway. In conclusion, a novel mechanism of muscle fiber injury in dysferlin-deficient muscular dystrophy is demonstrated, possibly opening therapeutic avenues in this to date untreatable disorder.

Adult↗