Macular Degeneration Research - Completed Award
Jonathan Haines, Ph.D.
Vanderbilt University Medical Center
Title: Genetic examination of AMD in the Midwestern Amish
Non-Technical Title: Genetic studies of age-related macular degeneration in Amish communities of Ohio and Indiana
Duration: April 1, 2008 - March 31, 2011
Award Type: Standard
Award Amount: $100,000
By examining a population with a close community and genetic similarities, this proposal will seek to identify genetic risk factors that predispose a population to AMD.
This study focuses on finding all the genetic components of AMD by examining people (the Amish) with large interrelated family and community structures who are more likely to share environmental exposures and underlying genetic structure than other average Americans. This will reduce the number of normal differences that occur in studies within the general population, and should make it easier to find the remaining genes involved in AMD. The goal is to identify novel factors to better understand AMD and provide other researchers with information for more effective treatments and preventative measures.
Age-related macular degeneration (AMD) is an eye disease found mostly in the elderly that causes debilitating vision loss. Several genes are known to increase the risk for developing AMD, but there are additional, as yet unidentified, AMD genes. Dr. Jonathan Haines and colleagues have been working with the elderly population (65 years and older) of well-defined and genetically-isolated Amish communities as part of a larger study of diseases in the aging population. The purpose of this project is to study these communities to discover new AMD genes.
Seventy three individuals, who are part of a single 1505-member Amish family, were examined by an eye specialist and also self reported whether they have or don’t have AMD. Forty two of those individuals were diagnosed with AMD, and thirty nine of the 42 diagnosed with AMD had self reported to have AMD. Thirty one individuals were determined to not have AMD, and only five of those individuals self reported to have AMD. Dr. Haines found the false positive rate of reporting AMD when AMD diagnosis was denied by an eye specialist to be 16%, and the false negative rate of not reporting previous AMD affection when an eye specialist confirmed AMD to be 7%. The positive predictive value (the percent of subjects who self reported they have AMD and are correctly diagnosed) is 89%, and the negative predictive value (the percent of subjects who self reported they don’t have AMD who end up being diagnosed with the disease) is 90%. Therefore, self reporting of AMD can be used as a reliable proxy for actual status of having AMD. Dr. Haines has already determined that a subset of the affected individuals do not have a known risk gene. Therefore, this unique Amish population provides the opportunity for discovering new genes associated with AMD.