A comparison of the lengths of androgen receptor triplet repeats in brain and blood in motor neuron diseases.
BACKGROUND
Expansions of triplet repeats are found in a number of neurodegenerative conditions, and different tissues in the same person can have varying repeat lengths. In Kennedy disease, motor neuron loss is due to expansion of the CAG repeat length in the androgen receptor gene (AR). We hypothesised that patients with other sporadic motor neuron diseases could have AR expansions that were restricted to CNS tissue.


METHODS
We measured the AR triplet repeat length in DNA extracted from the brains of 23 patients with sporadic amyotrophic lateral sclerosis (SALS) and 3 with sporadic progressive muscular atrophy (SPMA). Paired blood samples were available in 15 patients to look for blood-brain differences in CAG repeat length.


RESULTS
No CAG expansions in the Kennedy disease range were found in the SALS or SPMA brains. Furthermore, no brain-blood differences were found in the lengths of AR triplet repeats. Brain AR repeat length was not associated with the duration, or age or site of onset, of disease.


CONCLUSIONS
The findings indicate that a brain-specific expansion of AR triplet repeats is unlikely to underlie motor neuron loss in SALS or SPMA.
Saunderson
Rebecca B
RB
Department of Pathology, The University of Sydney, Australia.
Yu
Bing
B
Trent
Ronald J A
RJ
Pamphlett
Roger
R
D000328:Adult; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000378:metabolism* / Q000503:physiopathology; D016923:Cell Death / Q000235:genetics; D004252:DNA Mutational Analysis; D018450:Disease Progression; D005260:Female; D005819:Genetic Markers / Q000235:genetics; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005820:Genetic Testing; D006801:Humans; D008297:Male; D008875:Middle Aged; D016472:Motor Neuron Disease / Q000097:blood* / Q000235:genetics* / Q000503:physiopathology; D009154:Mutation / Q000235:genetics; D009410:Nerve Degeneration / Q000097:blood / Q000235:genetics / Q000503:physiopathology; D011944:Receptors, Androgen / Q000235:genetics*; D019680:Trinucleotide Repeat Expansion / Q000235:genetics*
D005819:Genetic Markers; D011944:Receptors, Androgen