Vision Loss in Elderly Caused By Combined Effect of Genes and Bacterium

A definitive link has been established between age-related macular degeneration and the genetic mechanisms underlying the disease process. The finding has been confirmed by the identification of a bacterium called Chlamydia pneumoniae in the diseased tissue of the affected individuals. It is also notable that the microorganism is associated with chronic inflammation and heart disease.

Researchers found C. pneumoniae in the diseased eye tissue of five of nine people with wet AMD. People without AMD (20) were however devoid of the microorganism and infection. Hence it is very possible that the disease itself is the result of an inflammatory process.

The microorganism C. pneumoniae is capable of modifying the function of important cell types involved in regulating normal eye function. Furthermore, the infection was associated with an increased production of vascular endothelial growth factor (VEGF), the key protein involved in wet AMD.

Researchers believe that nearly half of AMD cases can be explained by variations in a gene called Complement Factor H (CFH). The gene is known to play a significant role in the regulation of the natural immune and inflammatory response.

It is hence hypothesized that C. pneumoniae may be the key link between CFH and AMD, meaning that people who have different genetic constitution with respect to the CFH can be particularly susceptible to infections caused by the organism.

The increased susceptibility to infections followed by the presence of a chronic infection may accelerate inflammation and hence the progression of AMD in a certain groups of patients.

Further research is needed in the same direction to unravel the mysteries associated with the disease, which can help in better diagnosis and management.

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