Shorter women live longer, it’s in their genes

March 5th, 2008 - 3:06 pm ICT by admin  

Washington, March 5 (IANS) Nature rewards shorter women with extra long lives, according to a new study. Mutations in genes governing an important cell-signalling pathway influence human longevity, according to researchers at the Albert Einstein College of Medicine.

The study is based on a survey of more than 450 Ashkenazi (Eastern European) Jews aged between 95 and 110. It is the latest in the researchers’ ongoing search for genetic clues to longevity.

Findings of the study have been published in the latest issue of the Proceedings of the National Academy of Sciences.

Descended from a small group, Ashkenazis are more genetically uniform than other groups, making it easier to spot existing gene differences. In 2003, this study resulted in the first two “longevity genes” ever identified - findings that have since been validated by other research.

The latest study focussed on genes involved in the action of insulin-like growth factor (IGF-I), a hormone that is regulated by the human growth hormone. Affecting virtually every cell type in the body, IGF-I is crucially important for children’s growth and continues contributing to tissue synthesis into adulthood.

Animal research had shown that mutations to genes involved in the IGF-I signalling pathway cause two effects: Affected animals have impaired growth but also longer life spans.

So the Albert Einstein College scientists reasoned that altered signalling in this pathway might also influence human longevity.

They analysed IGF-I-related genetic variations in 384 Ashkenazi centenarians. And since plasma levels of IGF-I do not reflect their levels at a younger age, the researchers also looked at two other groups: their children, and a control group of other Ashkenazi counterparts with no history of longevity.

Remarkably, the centenarians’ female offspring had IGF-I plasma levels 35 percent higher than female controls, perhaps a sign that the body was compensating for a glitch in IGF-I signalling by secreting increased amounts of the hormone.

That suspicion was bolstered by two other findings: the daughters of centenarians were 2.5 cm shorter than female controls. Nir Barzilai of AECM pointed out that a drug that decreases IGF-I action is currently being tested as a cancer treatment and could be useful in delaying ageing.

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