Genetics
Genetics, in combination with environmental influences, have been found to play a key role in the development of AMD. Research laboratories throughout the world are working on identifying gene defects that make individuals more susceptible to developing AMD.
In 2005, a variation in the complement factor H gene (CFH) was found that substantially raises the risk of both wet and dry AMD. The CFH gene is located on chromosome 1and is part of the complement system, which is involved in inflammation.
Another important gene variant, ARMS2, is also strongly associated with AMD, but its function is not entirely known. Other genes involved in the complement pathway have been identified, including complement factors 2, 3, B and I (C2, C3, BF, CFI). Most recently, large studies have identified additional gene variants with smaller effects on the development of AMD. These include LIPC, CETP and a locus near TIMP3, along with others yet to be published.
Gene discoveries help investigators identify underlying mechanisms of disease, helping them develop new methods of prevention and treatment. In addition, they can help identify who is likely to develop AMD, and how they may respond to certain treatments.
The Role of Genes and Lifestyle Behaviors in Progression to Advanced AMD
Casey scientists, in collaboration with other investigators, have discovered that carriers of the CFH and ARMS2 gene variants are more likely to progress to the advanced form of the disease. The study also reported that lifestyle factors, such as smoking and body weight, increased the risk. When genetic information is available, it may in certain cases supplement other information, such as retinal findings and personal factors in determining when progression from early to advanced AMD is likely to occur.
Genes and AMD Therapies
Genetic makeup may also play a role in how patients respond to various treatments for AMD. Casey investigators found that an individual's response to the AREDS formulation of antioxidants and zinc may be affected by variations in the CFH and LOC387715 genes. However, studies by others show possible differences in response to various AMD treatments depending on the presence or absence of certain genetic variants.
Genetic Screening
Routine genetic screening for AMD is not recommended at this time. Additional research is needed to replicate and add to the findings thus far. Furthermore, more effective preventive measures are not yet available.
At this time, preventive measures like nutritional supplements can potentially benefit all patients at high risk of progressing to advanced AMD, regardless of their genetic makeup.
