Bi-allelic loss-of-function OBSCN variants predispose individuals to severe recurrent rhabdomyolysis

Macarena Cabrera-Serrano, Laure Caccavelli, Marco Savarese, Anna Vihola, Manu Jokela, Mridul Johari, Thierry Capiod, Marine Madrange, Enrico Bugiardini, Stefen Brady, Rosaline Quinlivan, Ashirwad Merve, Renata Scalco, David Hilton-Jones, Henry Houlden, Halil Ibrahim Aydin, Serdar Ceylaner, Sarah Drewes, Jerry Vockley, Rhonda L. TaylorChiara Folland, Aasta Kelly, Hayley Goullee, Emil Ylikallio, Mari Auranen, Henna Tyynismaa, Bjarne Udd, Alistair R.R. Forrest, Mark R. Davis, Drago Bratkovic, Nicholas Manton, Thomas Robertson, Cullen O'Gorman, Pamela McCombe, Nigel G. Laing, Liza Phillips, Pascale de Lonlay, Gianina Ravenscroft

Research output: Contribution to journalArticlepeer-review

1 Citation (Web of Science)

Abstract

Rhabdomyolysis is the acute breakdown of skeletal myofibres in response to an initiating factor, most commonly toxins and over exertion. A variety of genetic disorders predispose to rhabdomyolysis through different pathogenic mechanisms, particularly in patients with recurrent episodes. However, most cases remain without a genetic diagnosis. Here we present six patients who presented with severe and recurrent rhabdomyolysis, usually with onset in the teenage years; other features included a history of myalgia and muscle cramps. We identified 10 bi-allelic loss-of-function variants in the gene encoding obscurin (OBSCN) predisposing individuals to recurrent rhabdomyolysis. We show reduced expression of OBSCN and loss of obscurin protein in patient muscle. Obscurin is proposed to be involved in sarcoplasmic reticulum function and Ca2+ handling. Patient cultured myoblasts appear more susceptible to starvation as evidenced by a greater decreased in sarcoplasmic reticulum Ca2+ content compared to control myoblasts. This likely reflects a lower efficiency when pumping Ca2+ back into the sarcoplasmic reticulum and/or a decrease in Ca2+ sarcoplasmic reticulum storage ability when metabolism is diminished. OSBCN variants have previously been associated with cardiomyopathies. None of the patients presented with a cardiomyopathy and cardiac examinations were normal in all cases in which cardiac function was assessed. There was also no history of cardiomyopathy in first degree relatives, in particular in any of the carrier parents. This cohort is relatively young, thus follow-up studies and the identification of additional cases with bi-allelic null OBSCN variants will further delineate OBSCN-related disease and the clinical course of disease.
Original languageEnglish
Pages (from-to)3985-3998
Number of pages14
JournalBrain : a journal of neurology
Volume145
Issue number11
DOIs
Publication statusPublished - 21 Nov 2022

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