Genetics and Sex Affect RA

Christine Miller Health Guide
  • Women whose brothers are affected with erosive rheumatoid arthritis are more likely to also develop a severe form of the disease, according to research published in the October issue of Arthritis & Rheumatism. The study sought to build on prior research related to genetic factors and sex in arthritis by looking for clinical, genetic and demographic differences between male and female siblings. It is thought that incidence of RA is determined not by a single gene, but by several genes as well as environmental factors. The difficulty is pinpointing which ones and how they all interact.

    It is well known that RA affects women to men 3:1 and it is rarely seen in men under the age of 45. Although incidence of RA varies with age within each sex, prior studies have found some evidence that female sex hormones may be involved in RA onset. For example, pregnancy is associated with period of remission for many female patients while the postpartum period is associated with recurrence or new onset of the disease. Some studies (with conflicting data) also suggest that use of oral contraceptives over a period of time may be associated with a decrease in the severity of the disease. It is also known that there are several genetic factors that can affect people with RA and other autoimmune disorders.

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    This study included1,004 affected members of 467 Caucasian families in which two or more siblings have rheumatoid arthritis. The families were recruited by the North American Rheumatoid Arthritis Consortium. The researchers compared the disease features of women who had no brothers with RA to the features of women who had at least 1 brother with RA.

    The team found that men were more likely to show more signs of erosive disease and were more likely to test positive for rheumatoid factor and cyclic citrullinated peptides (CCP). Men with RA were also more likely to have a history of smoking and to have a gene called HLA-DRB1, a subtype of the genetic marker HLA-DR4 found in white blood cells, which is known to be associated with the disease. HLA-DRA assists the body in differentiating between its own cells and foreign cells that invade the body.
    Women whose brothers had RA also had higher anti-CCP antibodies and were more likely to have the HLA-DRB1 gene, compared to females whose brothers do not have RA. This finding supports the genetic evidence that RA, as well as other autoimmune disorders, runs in families.

    Patients should inform their doctors of a family history of RA and other autoimmune diseases. This information can assist the physician in determining the right course of treatment for the patient in the immediate and in the future as the disease progresses and changes.

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Published On: October 06, 2006