Amyloidosis as the Present Limited Factor on Human Lifespan
A theory that has emerged in recent years points to forms of amyloidosis as the final limiting process for human life span. Extremely long-lived people, who have survived or evaded all the common fatal age-related conditions, appear to die because of amyloid buildup. The evidence is good enough for the SENS Foundation to start funding work on a therapy - like all the mechanisms of aging, this is something that can be fixed through appropriate use of biotechnology. Here's a little more on the topic (and a link to a PDF format research paper): "Supercentenarians are persons who have lived beyond the age of 110. Currently there are only about 80 such known individuals in the world whose age is verified. These people represent the limit of human lifespan. For a variety of reasons not fully understood but including lifestyle choices, genetic variants, and chance, these individuals have escaped the usual causes of death including cancer, heart disease and stroke. However, eventually they too die, with the world record holder being Jeanne Calment who survived until age 122. In a newly published review Drs. Stephen Coles and Thomas Young of the UCLA Gerontology Research Group point out what it may be that is killing supercentenarians: amyloidosis. Amyloidosis is a disease state hallmarked by the deposition of fibers of abnormally clumped masses of transthyretin. The protein transthyretin normally acts to carry thyroid and other hormones. Mutations in the gene make the fibers abnormally sticky and they tend to clump into long fibers which are deposited in multiple organs. Through early onset amyloidosis leads to disease, it is of interests that supercentanarians all seem to have significant amounts of it. Though not proven it is possible the amyloid is killing them. These persons have already escaped the typical causes of death however they have lived for so long, the normally innocuous amounts of amyloid that increase with age may actually become toxic to them because they have lived so many years. Where this line of reasoning gets exciting is that experimental drugs exist which may eliminate amyloid."
Link: http://extremelongevity.net/2012/05/22/is-amyloidosis-the-limiting-factor-for-humans-lifespan/