The complement factor H (CFH) gene polymorphism is not associated with age-related macular degeneration (AMD) in the Japanese population. In fact, the frequency of the C allele is low among Japanese, according to the results of a genomic DNA cohort study we conducted among 67 Japanese patients with AMD and 107 controls.

Along with our colleagues from the Department of Ophthalmology and Visual Science, Graduate School of Biomedical Sciences and the Department of Epidemiology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima Japan, we published these results in Retina.1 Genetic factors have been reported in association with AMD, and recently four independent groups have reported a significant association with a common coding variant in the gene encoding CFH on chromosome 1q31. These studies, however, were performed in predominantly white populations.

In our study, we investigated whether polymorphism of CFH—the C allele of Y402H in exon 9—is associated with AMD in the Japanese population. We included two independent groups of Japanese people, those with AMD (n=67) and age- and sex-matched controls (n=107). The mean ±SD age of AMD patients and controls was 73 ±8.5 years and 72 ±8.7 years, respectively; 66% of the AMD patients and 51% of controls were male. The mean follow-up ±SD for AMD patients was 11 ±13 months.

When we investigated the polymorphism Y402H in exon 9 (Table 1), we found no significant difference between CFH genotypes in the AMD group and the control group. The frequency of C alleles was low among both AMD patients and the control group in our study.

The prevalence of neovascular AMD among ethnic population varies: 0.95% to 1.82% among whites, 0.67% among Japanese, and 0.11% to 0.48% among blacks. Age and smoking are well known risk factors for AMD, a complex genetic and environmental disorder.

It has been suggested that the risk variant of CFH in AMD may give rise of the complement deposition in choroidal capillaries and the choroidal vessel. Japanese patients had a better angiographic and vision outcome following photodynamic therapy for wet AMD than white patients. It may be possible that the different of disease susceptibility is related to the difference of the variant of the CFH gene between Japanese and white populations.

We suspect the low frequency of the C allele is one of the reasons for the low prevalence of AMD among Japanese compared with white populations.

Junko Uka, MD; Hiroki Tamura, MD; and Takayuki Kobayashi, MD, are from the Department of Ophthalmology and Visual Science, Hiroshima University, Japan. Atsushi Minamoto, MD, is from the Minamoto Eye Clinic, Hiroshima, Japan. He may be reached at minamoto@beach.ocn.ne.jp.

1. Uka J, Tamura H, Kobayashi T, et al. No association of complement factor H gene polymorphism and age-related macular degeneration in the Japanese population. Retina. 2006; 26: 985-987.