Huntingtin gene CAG repeat numbers in Chinese patients with Huntington's disease and controls.
OBJECTIVE
Huntington's disease is due to a CAG triplet repeat elongation in the huntingtin gene. Boundaries in CAG numbers have been found between healthy people with and without risk to pass the disorder to the next generation, and between people without, with a mild, or with a fully penetrant phenotype. These data have been generated in western populations and it is not clear whether they are also valid amongst Chinese.


METHODS
In order to establish normative data in the huntingtin gene for Chinese people, 966 chromosomes from normal controls were tested. Further, the range of CAG repeats was examined in a cohort from six centres and a total of 368 patients with the disease were included.


RESULTS
The CAG triplet repeat range in normal controls was between 9 and 35 (mean 18.9, SD 2.57). Triplets in the range between 26 and 35 were found in 2.5%. In the patient cohort, triplet repeats in the shorter allele were between 8 and 37 (mean 17.7, SD 1.6). In the longer allele, a range between 36 and 120 was found. There was a negative correlation (-0.65, r = 0.42) between age at onset and the number of triplet repeats in the larger allele. The mean age at onset was 38 years, with a range between 2 and 70 years. In 23 patients (6%) a childhood or juvenile onset was noted.


CONCLUSIONS
These data show comparable ranges of huntingtin gene CAG triplet repeats in normal people and in patients with Huntington's disease as in western populations.
Department of Neurology, Xiangya Hospital, Central South University, Changsha, China; Key Laboratory of Hunan Province in Neurodegenerative Disorders, State Key Laboratory of Medical Genetics of China, Central South University, Changsha, China.
H
H
Jiang
Y M
YM
Sun
Y
Y
Hao
Y P
YP
Yan
K
K
Chen
S H
SH
Xin
Y P
YP
Tang
X H
XH
Li
T
T
Jun
Y Y
YY
Chen
Z J
ZJ
Liu
C R
CR
Wang
H
H
Li
Z
Z
Pei
H F
HF
Shang
B R
BR
Zhang
W H
WH
Gu
Z Y
ZY
Wu
B S
BS
Tang
J-M
JM
Burgunder
D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D044466:Asian People / Q000208:ethnology / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D005787:Gene Frequency; D005820:Genetic Testing; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000235:genetics*; D012016:Reference Values; D018911:Trinucleotide Repeats / Q000235:genetics*; D055815:Young Adult
C086055:HTT protein, human; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins
CAG repeats; China; Huntington's disease; huntingtin gene; normative data