Purpose
The role of iron in the pathogenesis of age-related macular degeneration (AMD) is unknown. AMD-affected maculas have increased iron levels in Bruch’s membrane and the retinal pigment epithelium when compared to normal maculas. Hemochromatosis is a genetic disorder of iron metabolism associated with deposition of excess iron into tissues. The aim of this study is to investigate whether the hereditary hemochromatosis (HFE) H63D polymorphism is associated with advanced forms of AMD.
Methods
Cross-sectional analysis of patients seen at Penn State Hershey Eye Center with a diagnosis of AMD. The study protocol was approved by the Penn State College of Medicine Institutional Review Board. DNA was extracted from buccal swab specimens, and polymerase chain reaction amplification with restriction fragment length polymorphism analysis was performed to determine HFE H63D genotypes in each patient.
Results
128 patients were enrolled in the study and 120 samples were adequate for analysis. Each patient was categorized according to the type of AMD (dry AMD without geographic atrophy [GA], AMD with GA, or neovascular AMD) in the more severely affected eye. Baseline characteristics of all the patient groups are similar. 89 (74%) carry the wildtype genotype, 22 (18%) are heterozygous for the H63D mutation, and 8 (6%) are homozygous for the H63D mutation. Data were analyzed with patients with GA being categorized either as a form of dry AMD or included with the neovascular AMD group and classified as advanced AMD. When patients with GA are included in the group of patients with dry AMD, 36 (66%) dry AMD patients do not have the H63D mutation, 13 (24%) are heterozygotes, and 5 (9%) are homozygotes compared to 53 (81%) wet AMD patients who do not have the H63D mutation, 9 (13%) who are heterozygotes, and 3 (4%) who are homozygotes (p=0.1913). When patients with GA are included in the advanced AMD group, 60 (80%) advanced AMD patients do not have the H63D mutation, 11 (15%) are heterozygotes, and 4 (5%) are homozygous for the mutation. This is compared to patients with non-advanced AMD where 29 (66%) patients do not have the mutation, 11 (25%) are heterozygotes, and 4 (9%) are homozygotes (p=0.205). There was no significant difference in genotype distribution among patients with dry AMD without GA, dry AMD with GA, or neovascular AMD.
Conclusions
HFE H63D mutation status is not associated with advanced AMD.