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ABSTRACT: Objective
Limb girdle muscular dystrophy type R9 (LGMD R9) is an autosomal recessive muscle disease for which there is currently no causative treatment. The development of putative therapies requires sensitive outcome measures for clinical trials in this slowly progressing condition. This study extends functional assessments and MRI muscle fat fraction measurements in an LGMD R9 cohort across 6 years.Methods
Twenty-three participants with LGMD R9, previously assessed over a 1-year period, were re-enrolled at 6 years. Standardized functional assessments were performed including: myometry, timed tests, and spirometry testing. Quantitative MRI was used to measure fat fraction in lower limb skeletal muscle groups.Results
At 6 years, all 14 muscle groups assessed demonstrated significant increases in fat fraction, compared to eight groups in the 1-year follow-up study. In direct contrast to the 1-year follow-up, the 6-min walk test, 10-m walk or run, timed up and go, stair ascend, stair descend and chair rise demonstrated significant decline. Among the functional tests, only FVC significantly declined over both the 1- and 6-year studies.Interpretation
These results further support fat fraction measurements as a primary outcome measure alongside functional assessments. The most appropriate individual muscles are the vastus lateralis, gracilis, sartorius, and gastrocnemii. Using composite groups of lower leg muscles, thigh muscles, or triceps surae, yielded high standardized response means (SRMs). Over 6 years, quantitative fat fraction assessment demonstrated higher SRM values than seen in functional tests suggesting greater responsiveness to disease progression.
SUBMITTER: Murphy AP
PROVIDER: S-EPMC6562036 | biostudies-literature | 2019 Jun
REPOSITORIES: biostudies-literature
Murphy Alexander P AP Morrow Jasper J Dahlqvist Julia R JR Stojkovic Tanya T Willis Tracey A TA Sinclair Christopher D J CDJ Wastling Stephen S Yousry Tarek T Hanna Michael S MS James Meredith K MK Mayhew Anna A Eagle Michelle M Lee Laurence E LE Hogrel Jean-Yves JY Carlier Pierre G PG Thornton John S JS Vissing John J Hollingsworth Kieren G KG Straub Volker V
Annals of clinical and translational neurology 20190516 6
<h4>Objective</h4>Limb girdle muscular dystrophy type R9 (LGMD R9) is an autosomal recessive muscle disease for which there is currently no causative treatment. The development of putative therapies requires sensitive outcome measures for clinical trials in this slowly progressing condition. This study extends functional assessments and MRI muscle fat fraction measurements in an LGMD R9 cohort across 6 years.<h4>Methods</h4>Twenty-three participants with LGMD R9, previously assessed over a 1-yea ...[more]