Preeclampsia – a dangerous rise in blood pressure in pregnant women – has been linked to a genetic variant found in the baby, instead of the mother.
'Over the years, people have looked at mothers' genes', said lead author Dr Linda Morgan of the University of Nottingham. 'This is the first large study to look at babies' genes'.
The study, published in Nature Genetics, carried out a genome-wide association study (GWAS) to compare 4380 mothers and children affected by preeclampsia with over 300,000 pairs who were not, in England, Iceland, Norway and Finland. It identified DNA variations near the gene FLT1 as being linked to increased risk of preeclampsia. FLT1 is involved in blood vessel formation and had been previously linked to preeclampsia.
The study is the first to show an effect of fetal DNA on the health of a mother.
Identifying FLT1 in the child 'makes a lot of sense', says Dr Ananth Karumanchi, a vascular biologist at Beth Israel Deaconess Medical Centre in Boston, who was not involved in the study. Preeclampsia is thought to start in the placenta, which mainly consists of cells from the fetus.
The gene variant was only associated with one subtype of preeclampsia: late-onset preeclampsia, which develops after 34 weeks of gestation. A baby carrying one copy of the gene variant would increase the mother's risk of preeclampsia by about 20 percent.
Although the finding might lead to better treatment in the future, Dr Morgan is cautious: 'The importance of these findings lies in the insights which they give to the underlying mechanisms that lead to pre-eclampsia'. She added that other risk factors are known to be much stronger, including previous high blood pressure or carrying twins.
Preeclampsia affects about one in 20 women during the second half of their pregnancy and is marked by high blood pressure and proteins in the mother's urine. If left untreated, it can lead to seizures in the mother which can be fatal to her or the fetus.
'Because pre-eclampsia has its origins in the very early stages of pregnancy, during the formation of the placenta, research into the causes and processes of the disease has always been challenging,' said Dr Morgan. 'Now modern genome wide screening and its data analysis allows us to look for clues in the mother's, father's and their baby's DNA.'
The team are currently testing the DNA of a further 4220 babies from Kazakhstan and Uzbekistan for the same genetic variant.