Comprehensive analysis of the candidate genes CCL2, CCR2, and TLR4 in age-related macular degeneration.
OBJECTIVE
To determine whether variants in the candidate genes TLR4, CCL2, and CCR2 are associated with age-related macular degeneration (AMD).


METHODS
This study was performed in two independent Caucasian populations that included 357 cases and 173 controls from the Netherlands and 368 cases and 368 controls from the United States. Exon 4 of the TLR4 gene and the promoter, all exons, and flanking intronic regions of the CCL2 and CCR2 genes were analyzed in the Dutch study and common variants were validated in the U.S. study. Quantitative (q)PCR reactions were performed to evaluate expression of these genes in laser-dissected retinal pigment epithelium from 13 donor AMD and 13 control eyes.


RESULTS
Analysis of single nucleotide polymorphisms (SNPs) in the TLR4 gene did not show a significant association between D299G or T399I and AMD, nor did haplotypes containing these variants. Univariate analyses of the SNPs in CCL2 and CCR2 did not demonstrate an association with AMD. For CCR2, haplotype frequencies were not significantly different between cases and controls. For CCL2, one haplotype containing the minor allele of C35C was significantly associated with AMD (P = 0.03), but this did not sustain after adjustment for multiple testing (q = 0.30). Expression analysis did not demonstrate altered RNA expression of CCL2 and CCR2 in the retinal pigment epithelium from AMD eyes (for CCL2 P = 0.62; for CCR2 P = 0.97).


CONCLUSIONS
No evidence was found of an association between TLR4, CCR2, and CCL2 and AMD, which implies that the common genetic variation in these genes does not play a significant role in the etiology of AMD.
Despriet
Dominiek D G
DD
Department of Clinical and Molecular Ophthalmogenetics, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, The Netherlands.
Bergen
Arthur A B
AA
Merriam
Joanna E
JE
Zernant
Jana
J
Barile
Gaetano R
GR
Smith
R Theodore
RT
Barbazetto
Irene A
IA
van Soest
Simone
S
Bakker
Arne
A
de Jong
Paulus T V M
PT
Allikmets
Rando
R
Klaver
Caroline C W
CC
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D018932:Chemokine CCL2 / Q000235:genetics*; D004252:DNA Mutational Analysis; D005091:Exons / Q000235:genetics; D005260:Female; D006239:Haplotypes; D006801:Humans; D008268:Macular Degeneration / Q000175:diagnosis / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D054390:Receptors, CCR2 / Q000235:genetics*; D051197:Toll-Like Receptor 4 / Q000235:genetics*; D044465:White People / Q000235:genetics
C111835:CCL2 protein, human; C515334:CCR2 protein, human; D018932:Chemokine CCL2; D054390:Receptors, CCR2; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4