A child’s genetic makeup may contribute to his or her mother's risk of rheumatoid arthritis, possibly explaining why women are at higher risk of developing the disease than men. This research was presented Tuesday, October 21, at the American Society of Human Genetics (ASHG) 2014 Annual Meeting in San Diego, Californai. Rheumatoid arthritis, a painful inflammatory condition that primarily affects the joints, has been tied to a variety of genetic and environmental factors, including lifestyle factors and previous infections. Women are three times more likely to develop rheumatoid arthritis than men, with peak rates among women in their 40s and 50s. Certain versions of the immune system gene HLA-DRB1, known collectively as the shared epitope alleles, are associated with the condition. HLA genes are best known for their involvement in the immune system’s response to infection and in transplant medicine for differentiating between one’s own cells and those that are foreign. The female predilection of rheumatoid arthritis strongly suggests that factors involved in pregnancy are involved, said Giovanna Cruz, MS, graduate student at the University of California, Berkeley, and first author on the new study. “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,” Ms. Cruz said. “Why it happens, we don’t know, but we suspect HLA genes and their activity may be involved,” she explained.Login Or Register To Read Full Story