The current research results indicate that one fairly rare mitochondrial haplogroup found in only 2% of all Europeans - which is known as 'haplogroup X' - was found in 15% of the successfully aged Amish population (versus only 3% of the controls) and had a significant positive association with successful aging. On the other hand, the researchers also reported that another mitochondrial haplogroup called 'haplogroup J' which is typically found in about 10-25% of Southern Europeans, was found in only 5% of the Amish population and had a negative association with successful aging factors.

Thus, a significant positive association with successful aging was found with mitochondrial haplogroup X (which was more prevalent among the successfully aged Amish population), while a negative association was found with haplogroup J (which is more prevalent in European populations than the Amish). All positively associated alleles were found together on haplogroup X, while all negatively associated alleles fell in haplogroup J. All positively associated alleles were found together on haplogroup X (1719A), while all negatively associated alleles fell in haplogroup J (rs2854122, rs3135030, and 10398G). These data represent a novel association of mitochondrial haplogroup X with successful aging that conflicts with previous positive associations of haplogroup J with longevity in other populations.

"In this study, we focused on looking for genes that may have an influence on keeping people healthy, rather than identifying genes associated with disease," said William Scott, PhD, the senior author of the research abstract presented at the ASHG 2010 Annual Meeting. "Our research results support the idea that mitochondria play an important role in aging, and our findings also suggest a specific subset of genetic variants that might influence successful aging in this group of people."

"In our future research, it is important that we attempt to broadly associate this mitochondrial variation to aging in this population, figure out what it does biologically, and then see if we can reproduce it in other samples," said Scott. "Furthermore, we will also need to look more closely at the mitochondrial genome for specific variants that influence aging."

Source: American Society of Human Genetics