Analysis of glutathione S-transferase Pi isoform (GSTP1) single-nucleotide polymorphisms and macular telangiectasia type 2.
Recent imaging studies have suggested that macular pigment is decreased centrally in macular telangiectasia type 2 (MT2). The uptake of xanthophyll pigment into the macula is thought to be facilitated by a xanthophyll-binding protein (XBP). The Pi isoform of glutathione S-transferase (GSTP1) represents one such XBP with high binding affinity. This case-control study aimed to determine whether two common single-nucleotide polymorphisms (SNPs) of GSTP1 were associated with MT2. DNA samples from 39 cases and 21 controls were collected. Two polymorphic sites of Ile105Val and Ala114Val in exons 5 and 6 respectively, of the GSTP1 gene were analysed. Comparison of alleles and genotypes between cases and controls indicated that there were no statistically significant differences for either the Ile105Val SNP (P=0.43) or the Ala114Val SNP (P=0.85), or for any combinations; however, the homozygous at-risk genotype (GG) of the Ile105Val SNP was present in 8% of cases but absent in controls. This study found no statistically significant association between two common GSTP1 SNPs and MT2; however, a trend towards a greater frequency of the GG genotype of the Ile105Val SNP in cases is of great interest. The biological plausibility of disturbed macular pigment uptake in MT2 makes GSTP1 an excellent candidate gene. Further investigation is warranted in future studies of MT2.
Szental
Joshua A
JA
The Alfred Hospital, Commercial Road, Prahran, Melbourne, VIC, 3181, Australia. jszental@gmail.com
Baird
Paul N
PN
Richardson
Andrea J
AJ
Islam
F M Amirul
FM
Scholl
Hendrik P N
HP
Charbel Issa
Peter
P
Holz
Frank G
FG
Gillies
Mark
M
Guymer
Robyn H
RH
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D051549:Glutathione S-Transferase pi / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D008266:Macula Lutea / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D012171:Retinal Vessels; D013684:Telangiectasis / Q000235:genetics*
C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi