Axonal neuropathy in female carriers of the fragile X premutation with fragile x-associated tremor ataxia syndrome.
BACKGROUND
In this study we examined whether females with the fragile X-associated tremor ataxia syndrome (FXTAS) and non-FXTAS premutation carriers have electrophysiological signs of underlying peripheral neuropathy.


METHODS
Nerve conduction studies (NCS) were performed on 19 women with FXTAS, 20 non-FXTAS carriers, and 26 age-matched controls. The results were compared with existing data on corresponding male carriers.


RESULTS
Women with FXTAS and non-FXTAS carriers had reduced sensory nerve action potential amplitudes. Also, there was a strong trend for reduced compound muscle action potential amplitudes in women with FXTAS, but not in non-FXTAS carriers. No significant slowing of nerve conduction velocities, prolongation of F-wave latencies, or associations with molecular measures was observed.


CONCLUSIONS
This study suggests an underlying axonal neuropathy in women with FXTAS. However, in comparison to men with FXTAS, the NCS abnormalities in women were less severe, possibly due to the effect of a normal X chromosome.
Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis Medical Center, 2825 50th Street, Sacramento, California, 95817, USA.
Suresh
S
Ram
Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis Medical Center, 2825 50th Street, Sacramento, California, 95817, USA.
Inoka A
IA
Devapriya
Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis Medical Center, 2825 50th Street, Sacramento, California, 95817, USA.|Department of Neurology, University of California Davis Health System, Sacramento, California, USA.
Grace
G
Fenton
Division of Biostatistics, University of California Davis, Davis, California, USA.
Lindsey
L
Mcvay
Department of Medicine, University of California Irvine, Orange, California, USA.
Danh V
DV
Nguyen
Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis Medical Center, 2825 50th Street, Sacramento, California, 95817, USA.|Department of Biochemistry and Molecular Medicine, University of California Davis, Davis, California, USA.
Flora
F
Tassone
Department of Neurology, University of California Davis Health System, Sacramento, California, USA.
Ricardo A
RA
Maselli
Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis Medical Center, 2825 50th Street, Sacramento, California, 95817, USA.|Department of Pediatrics, University of California Davis Health System, Sacramento, California, USA.
Randi J
RJ
Hagerman
D000368:Aged; D001259:Ataxia / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics*; D001369:Axons / Q000473:pathology*; D015331:Cohort Studies; D005260:Female; D005600:Fragile X Syndrome / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D009431:Neural Conduction / Q000502:physiology; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics*; D014202:Tremor / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics*
FMR1; FXTAS; fragile X permutation; fragile X-associated tremor ataxia syndrome; nerve conduction studies