Tuesday, July 3, 2018

Lamin A/C congenital muscular dystrophy

Inspired by a patient

Azibani F, Brull A, Arandel L, Beuvin M, Nelson I, Jollet A, Ziat E, Prudhon B, Benkhelifa-Ziyyat S, Bitoun M, Lorain S, Bonne G, Bertrand AT. Gene Therapy via Trans-Splicing for LMNA-Related Congenital Muscular Dystrophy. Mol Ther Nucleic Acids. 2018 Mar 2;10:376-386.

We assessed the potential of Lmna-mRNA repair by spliceosome-mediated RNA trans-splicing as a therapeutic approach for LMNA-related congenital muscular dystrophy. This gene therapy strategy leads to reduction of mutated transcript expression for the benefit of corresponding wild-type (WT) transcripts. We developed 5'-RNA pre-trans-splicing molecules containing the first five exons of Lmna and targeting intron 5 of Lmna pre-mRNA. Among nine pre-trans-splicing molecules, differing in the targeted sequence in intron 5 and tested in C2C12 myoblasts, three induced trans-splicing events on endogenous Lmna mRNA and confirmed at protein level. Further analyses performed in primary myotubes derived from an LMNA-related congenital muscular dystrophy (L-CMD) mouse model led to a partial rescue of the mutant phenotype. Finally, we tested this approach in vivo using adeno-associated virus (AAV) delivery in newborn mice and showed that trans-splicing events occurred in WT mice 50 days after AAV delivery, although at a low rate. Altogether, while these results provide the first evidence for reprogramming LMNA mRNA in vitro, strategies to improve the rate of trans-splicing events still need to be developed for efficient application of this therapeutic approach in vivo.

Karaoglu P, Quizon N, Pergande M, Wang H, Polat AI, Ersen A, Özer E, Willkomm L, Hiz Kurul S, Heredia R, Yis U, Selcen D, Çirak S. Dropped head congenital muscular dystrophy caused by de novo mutations in LMNA. Brain Dev. 2017 Apr;39(4):361-364.

Dropped head syndrome is an easily recognizable clinical presentation of Lamin A/C-related congenital muscular dystrophy. Patients usually present in the first year of life with profound neck muscle weakness, dropped head, and elevated serum creatine kinase.

Two patients exhibited head drop during infancy although they were able to sit independently. Later they developed progressive axial and limb-girdle weakness. Creatine kinase levels were elevated and muscle biopsies of both patients showed severe dystrophic changes. The distinctive clinical hallmark of the dropped head led us to the diagnosis of Lamin A/C-related congenital muscular dystrophy, with a pathogenic de novo mutation p.Glu31del in the head domain of the Lamin A/C gene in both patients. Remarkably, one patient also had a central involvement with white matter changes on brain magnetic resonance imaging.

Lamin A/C-related dropped-head syndrome is a rapidly progressive congenital muscular dystrophy and may lead to loss of ambulation, respiratory insufficiency, and cardiac complications. Thus, the genetic diagnosis of dropped-head syndrome as L-CMD and the implicated clinical care protocols are of vital importance for these patients. This disease may be underdiagnosed, as only a few genetically confirmed cases have been reported.

Heller F, Dabaj I, Mah JK, Bergounioux J, Essid A, Bönnemann CG, Rutkowski A, Bonne G, Quijano-Roy S, Wahbi K. Cardiac manifestations of congenital LMNA-related muscular dystrophy in children: three case reports and recommendations for care. Cardiol Young. 2017 Aug;27(6):1076-1082.

Skeletal and cardiac muscle laminopathies, caused by mutations in the lamin A/C gene, have a clinical spectrum from congenital LMNA-related muscular dystrophy to later-onset Emery-Dreifuss muscular dystrophy, limb girdle muscular dystrophy, and dilated cardiomyopathy. Although cardiac involvement is observed at all ages, it has only been well described in adults. We present the evolution of cardiac disease in three children with congenital muscular dystrophy presentation of LMNA-related muscular dystrophy. In this series, atrial arrhythmia was the presenting cardiac finding in all three patients. Heart failure developed up to 5 years later. Symptoms of right heart failure, including diarrhoea and peripheral oedema, preceded a rapid decline in left ventricular ejection fraction. Recommendations for cardiac surveillance and management in these patients are made.

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