Here is the initial explanation from the press release:
Scientists at BYU and several other leading Alzheimer’s research institutions have discovered a rare genetic mutation that increases the risk of Alzheimer’s disease.One of the keys to this discovery was the examination of pedigrees:
The international team of researchers report in this week’s issue of the New England Journal of Medicine that a rare variant of TREM2, a gene associated with the immune system, is linked to a higher risk of Alzheimer’s.
The methodology for this study was also important, according to Kauwe and Carlos Cruchaga, assistant professor of psychiatry at Washington University, who led the study. Cruchaga said it will open new doors to understanding the disease and how gene variants affect risk, either in combination or alone.Perhaps as genealogists we have been too casual in our consideration of the importance of the research we could do? What if our databases contained information on the illnesses and cause of death of hundreds of thousands of people. Wouldn't that information be useful in this type of research? Isn't it important to know that you and your family may have a propensity for a crippling and deadly disease? It might be interesting to start extending our research to include the cause of death and any major illnesses suffered by our ancestors whenever that information is possible to acquire. Just a thought.
They took a different approach to finding the variants. Instead of taking a scattershot approach and looking at the largest number of subjects possible, they selected pedigrees that had interesting patterns of inheritance and were already identified as having multiple members with Alzheimer's, then drilled down to find the actual genetic variants.
Washington University identified and evaluated families, finding a number of things researchers wanted to focus on, then asked BYU researchers to help examine those questions.