Brona McVittie reports :: November 2008

The early environment of a developing child can talk to its genome by epigenetic means. Environmental cues trigger changes to epigenetic tags on our genome, which shape the way genes are expressed. These tags on the genome can be carried through from cell to cell as we replace damaged body tissue. When such changes occur inside egg or sperm cells, they can pass through to the next generation. So, we don’t just inherit our genes, but potentially also their modes of expression.

A recent study published in Diabetes by Josep Jimenez–Chillaron and colleagues on 19th November adds further strength to this argument.  Based on recent research, which indicates that low birth weight is associated with increased risk of obesity, diabetes and cardiovascular disease during adult life, the team wanted to know whether such disease risks might be passed on to future generations.
 
They bred mice with low birth weight by starving pregnant mothers during the last week of pregnancy.  Animals with low birth weight were mated and compared to the offspring from normal crosses. The experimental results indicated that starving pregnant mothers “programs” a low birth weight not only in her infants, but those of the next generation.

Coupled with this, males from the first-generation crosses were found to be glucose intolerant, which increased with age. All of the subsequent generation developed glucose intolerance by four months. Other studies have confirmed that diabetes can pass through more than a single generation through the maternal line, but this is the first study that shows inheritance of glucose intolerance through the male line.

Exactly how such changes manifest at the molecular level remains to be fully elucidated, although the team pinpointed a gene called Sur1, which could be linked to the glucose intolerance. While the researchers haven’t yet established the epigenetic basis of this inheritance, further studies will investigate changes to epigenetic tags that might be responsible. Such research has important medical implications, but will also cast light on the role of epigenetics in evolution.