You are what your dad’s mum ate
By examining the harvest records of a village in North Sweden, scientists have shown a link between the paternal grandmothers’ early-life diet and the risk of heart disease in their granddaughters.
The findings, published in BMC Genetics, focused on people in Överkalix, Sweden, who experienced drastic changes in their diet, either a good harvest followed by a poor one or vice versa, and their descendents. Women who had experienced drastic changes to their diet before they were 12 appeared to pass on a higher than average risk of heart disease to their sons’ daughters. In contrast, their sons’ sons and all the offspring of their daughters showed no such effect on cardiovascular health, nor did the grandchildren of men who experienced drastic changes in harvests.
The strange pattern of inheritance, the authors suggest, might be because a drastic change between high and low supplies of food created an epigenetic mark on the X chromosome, which would be lost where a grandfather passed on a Y chromosome to a boy somewhere in the line, or where there is mixing between marked and unmarked X chromosomes in women.
Epigenetics describes heritable changes to gene activity that are not changes to the DNA sequence or genes. These can be caused by environmental factors, and the mechanism by which these are passed on is not fully understood. It is thought that they are chemical marks attached to the molecules making up the genome.
The researchers used Överkalix, because it was isolated in the 19th century, and residents were unable to reach other towns during the winter when there was bad weather. This meant that the town was completely reliant on its own harvest for food supplies during this time, and records of the harvest are a good indicator of how much food was available to people during the year. The town also has good records of the birthdates and family trees of the people living there, so it was possible to trace the grandchildren of people who had lived through a drastic change to the availability of food.
The years chosen were 1799-1800, 1876-77 and 1880-81, when a very good harvest was followed by a bad, and 1812-13 and 1821-22 when a year of scarcity was followed by a year of plenty. The scientists found examples of men and women who had or hadn’t experienced these changes to food supply and compared their grandchildren’s rates of heart disease.
Parental occupation, literacy and gender were taken into account in the analysis but they did not affect the finding that disease risk was linked to the Grandmother’s diet.
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Notes to Editor
1. Change in paternal grandmothers' early food supply influenced cardiovascular mortality of the female grandchildren.
Bygren L, Tinghög P, Carstensen J, Edvinsson S, Kaati G, Pembrey M and Sjöström M
BMC Genetics 2014, 15:12
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