Rheumatoid arthritis affects 580,000 people in England and Wales.
Women are three times more likely to develop the condition than men and the
team at University of California Berkeley believe the presence of certain
high risk cells in the free fetal DNA may be the reason.
They found that if the baby inherited certain genes, grouped as HLA genes,
then the mother was more likely to have rheumatoid arthritis.
The findings are being presented on Tuesday at American Society of Human
Genetics 2014 Annual Meeting in San Diego.
Giovanna Cruz, is a graduate student at the University of California,
Berkeley, and first author on the new study.
She said: “During pregnancy, you’ll find a small number of fetal cells
circulating around the mother’s body, and it seems that in some women, they
persist as long as several decades.
“Women with rheumatoid arthritis are more likely to have this persistence
of fetal cells, known as fetal microchimerism, than women without the
condition, suggesting that it is a potential risk factor for the development
of rheumatoid arthritis.
“Why it happens, we don’t know, but we suspect HLA genes and their
activity may be involved,†she explained.
In addition to explaining why women are at increased risk of rheumatoid
arthritis, the findings may lead to new ways of assessing a woman’s risk of
disease depending on whether her children or partner carries high-risk
versions of genes.
This will form future research projects Ms Cruz said.
Other future research includes genetically analysing multiple generations of
rheumatoid arthritis cases, including mothers of people with the disease,
and further exploring the role of HLA-encoded proteins and microchimerism.