A new study found a rare mutation that changes a letter in the genetic code has been found to protect people from Alzeimer's disease. This reported mutation involves the gene called APP, which codes for a protein that gets broken down into pieces. In previous studies, scientists have identified more than 30 mutations in this gene but none were found to be advantageous.

In a new study conducted by Karl Stefansson and team at deCODE genetics in Iceland, variations in APP of 1795 individuals were evaluated. The team found one particular variant that stood out: a switch in a nucleotide at a specific location in the gene. Those who had this mutation were 7.5 times less likely to have Alzheimer's disease than those who do not have it.

Read the original article at http://news.sciencemag.org/sciencenow/2012/07/gene-mutation-protects-against-a.html. The research report is available in Nature: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature11283.html.