Alzheimer’s disease is a memory loss disease that occurs to the people in the age of around 70 to 80 years. Scientists say that a rare mutation in the DNA that changes a single letter in the genetic code can be a cure for this disease. As a result of this mutation, there is an increase in the amount of beta amyloid. It is a protein fragment that usually gets accumulated in the hallmark plaques, which forms in the patient’s brain. The researchers say that these findings are not only interesting and challenging rather than surprising.
There is a gene called as the APP gene which gets affected and breaks down into smaller pieces, along with the beta amyloid after this gene mutation. Scientists have studied previously about more than 30 changes or mutations that affected this gene but none of them were found to be useful. Many of these mutations , increased the amount of beta amyloid and formed a devastating form of Alzheimer’s that afflicted the people in their early age of 30’s and 40’s which is much in advance to the normal Alzheimer’s that comes to the people in the age of 70’s and 80’s.
The new mutation that is found now, is a total opposite to the above process. A team of researchers at DeCODE genetics in Reykjavik led by Stefansson extracted whole genetic data from around 1795 Icelanders to study the variations in the APP gene. After the study , they found one common thing, a single nucleotide has changed in the APP gene at one particular position. Among the Icelanders, people above the age of 85 who had this mutation was seven times less likely to have the Alzheimer’s disease than the people who did not have it.
Some additional experiments were done on the cultured cells of these recovered patients. The results suggested that the mutation intervenes with one enzyme that is responsible for the breakage of APP gene and thus causing a 40% reduction in the beta amyloid present. So ultimately, it can be concluded that the increased amount of beta amyloid was the main reason for this disease. This is called as the amyloid hypothesis.
Before this gene mutation was discovered, there was a naturally occurring mutation in a different gene called the APOE2 allele which also protected from the Alzheimer’s disease. But Stefansson says the APP gene mutation has more protection than the previous one and that this new gene mutation can even protect memory loss and other cognitive worsening even in people who do not have the Alzheimer’s disease.
There are some mishaps even in this amyloid hypothesis for the Alzheimer’s patients. In the recent years, the trials that involve drugs that tend to reduce the amount of beta amyloid had some disappointing results also. The researchers say this failure may be due to late start up of the remedy, because it did so many irreversible changes in the brain. So clinical trials are now done by giving these drugs to the patients in the early onset of the disease rather than at the later stage.