HTRA1 variants in exudative age-related macular degeneration and interactions with smoking and CFH.
OBJECTIVE
Mapping the genes for age-related macular degeneration (AMD) had not been successful until recent genome-wide association studies revealed Tyr402His in CFH and rs11200638 in HTRA1 as AMD-related genetic variants. This study was conducted to identify other critical factors in HTRA1 that are associated with exudative AMD.


METHODS
The promoter, splice regions, and coding exons of HTRA1 were sequenced in 163 patients with exudative AMD and 183 sex- and age-matched control subjects. Also documented were the CFH genotype and smoking status.


RESULTS
Four significant SNPs were found in the promoter and the first exon of HTRA1: rs11200638 (-625G>A), rs2672598 (-487T>C), rs1049331 (102C>T, Ala34Ala), and rs2293870 (108G>T, Gly36Gly) with respective P = 1.7 x 10(-14), 3.0 x 10(-10), 3.7 x 10(-12), and 3.7 x 10(-12). Among them, rs11200638 is the most significant associated SNP with a high odds ratio (OR) of 7.6 (95% CI: 3.94-14.51). One risk haplotype block across the promoter and exon 1, ACCTT, significantly predisposes to AMD (P = 6.68 x 10(-14)). In both models, significant independent additive effects were identified with smoking and rs800292 (184G>A, Val62Ile) of CFH. Smoking and rs11200638 (HTRA1) combined caused a 15.7-fold increased risk, whereas combined rs800292 and rs11200638 caused a 23.3-fold increased risk. An extremely high population attributable risk (PAR) of 78% was also found.


CONCLUSIONS
A high impact of the additive effect of CFH and HTRA1 in the development of exudative AMD was shown. The HTRA1-smoking additive effect found in this study further suggests the importance of this environmental risk factor in AMD.
Tam
Pancy O S
PO
Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.
Ng
Tsz Kin
TK
Liu
David T L
DT
Chan
Wai Man
WM
Chiang
Sylvia W Y
SW
Chen
Li Jia
LJ
DeWan
Andrew
A
Hoh
Josephine
J
Lam
Dennis S C
DS
Pang
Chi Pui
CP
D000368:Aged; D000369:Aged, 80 and over; D017242:Complement Factor H / Q000235:genetics; D005091:Exons / Q000235:genetics; D005122:Exudates and Transudates; D005260:Female; D006239:Haplotypes; D000074289:High-Temperature Requirement A Serine Peptidase 1; D006801:Humans; D008268:Macular Degeneration / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic / Q000235:genetics; D012307:Risk Factors; D017422:Sequence Analysis, DNA; D012697:Serine Endopeptidases / Q000235:genetics*; D012907:Smoking / Q000235:genetics*
C493495:CFH protein, human; D017242:Complement Factor H; D000074289:High-Temperature Requirement A Serine Peptidase 1; C474012:HTRA1 protein, human; D012697:Serine Endopeptidases