Father of woman's children may determine her risk of rheumatoid arthritis: study

According to new research, women may develop rheumatoid arthritis as a result of having children with men carrying high risk genes, Telegraph.co.uk reports.

Cells from the baby can leak into the mother's bloodstream during pregnancy and in some women remain there for decades. They were thought harmless but now it has been found that if they contain certain high risk genes, which the child inherited from its father, then the mother may be at greater risk of rheumatoid arthritis.

In some women their own immune system attacks the baby's cells, known as free fetal DNA, as if they were a foreign invader like an infection, and it is thought this may trigger rheumatoid arthritis.

Unlike osteoarthritis, which mostly occurs in old age, rheumatoid arthritis strikes at all ages, particularly middle-age and is caused by the immune system attacking the body's joints.

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.

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