Gd. Mellick et al., The monoamine oxidase B gene GT repeat polymorphism and Parkinson's disease in a Chinese population, J NEUROL, 247(1), 2000, pp. 52-55
Monoamine oxidase B (MAOB) metabolises dopamine and activates neurotoxins k
nown to induce parkinsonism in humans and primates. Therefore the MAOB gene
(MAOB; Xp15.21-4) is a candidate gene for Parkinson's disease (PD). Longer
length dinucleotide repeat sequences in a highly polymorphic GT repeat reg
ion of intron 2 of this gene showed an association with PD in an Australian
cohort. We repeated this allele-association study in a population of 176 C
hinese PD patients (90 men, 86 women) and 203 age-matched controls (99 men,
104 women). Genomic DNA was extracted from venous blood and the polymerase
chain reaction was used to amplify the appropriate regions of the MAOB gen
e. The length of each (GT) repeat sequence was determined by 5% polyacrylam
ide denaturing gel electrophoresis. There was no significant difference in
allele frequencies of the (GT) repeat allelic variation between patients an
d controls (chi(2) = 2.48; df = 5, P < 0.75). Therefore the longer length G
T repeat alleles are not associated with PD in this Chinese population. Pos
sible reasons for the discrepancy between Chinese and Australian population
s include a different interaction between this genetic factor and environme
ntal factors in the two populations and the possibility that the long lengt
h GT repeat alleles may represent a marker mutation, genetically linked to
another susceptibility allele in whites but not in Chinese. Methodological
differences in the ascertainment of cases and controls in this cohort could
also explain the observed differences. Further study is required to determ
ine whether the longer length GT repeat alleles are true susceptibility all
eles in PD.