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Functional motor control deficits in older FMR1 premutation carriers
Seoung Hoon Park1, Zheng Wang2, Walker McKinney3,4,5
1Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.
Experimental Brain Research
|June 5, 2019
Summary
Older individuals with the FMR1 premutation show motor control deficits, including greater force variability and reduced stepping velocity. These findings in FMR1 premutation carriers may indicate early signs of FXTAS or subclinical motor impairments.
Area of Science:
- Neuroscience
- Genetics
- Motor Control
Background:
- Individuals with fragile X mental retardation 1 (FMR1) gene premutations have an increased risk for fragile X-associated tremor/ataxia syndrome (FXTAS).
- It remains unclear if older FMR1 premutation carriers, with or without FXTAS, exhibit functional motor control deficits compared to healthy individuals.
Purpose of the Study:
- To determine if older FMR1 premutation carriers exhibit impaired functional motor task performance.
Main Methods:
- Eight FMR1 premutation carriers and eight age/sex-matched healthy controls performed isometric force control and single-step tasks.
- Motor unit firing rates in the first dorsal interosseous (FDI) muscle were recorded during a finger abduction task.
Main Results:
- FMR1 premutation carriers showed significantly greater force variability during isometric force control compared to controls (P=0.04).
- Carriers exhibited reduced multiple motor unit firing rates during steady force tasks.
- Reduced weight transfer velocity was observed in FMR1 premutation carriers during stepping (P=0.01).
Conclusions:
- Older FMR1 premutation carriers demonstrate functional motor control deficits.
- These deficits may represent subclinical issues related to FMR1 premutations, independent of FXTAS.
- Alternatively, these findings could indicate prodromal markers for the development of FXTAS.
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