By Mayo Clinic News Network

Rheumatoid arthritis occurs in people across the world. It appears that some people may be genetically predisposed to develop the disorder, which develops when your body's immune system mistakenly attacks the tissue that lines certain joints. The inflammation associated with rheumatoid arthritis damages and may deform the affected joints.

Environmental factors, such as airborne lung irritants, may trigger rheumatoid arthritis in people who are genetically predisposed to develop the disorder. Factors that may increase your risk of rheumatoid arthritis include:

  • Your sex. Women are at least twice as likely as men to have rheumatoid arthritis.
  • Age. Rheumatoid arthritis most commonly begins between the ages of 40 and 60.
  • Family history. If a member of your family has rheumatoid arthritis, you may have an increased risk of the disease.
  • Environmental factors. Substances that may act as triggers for rheumatoid arthritis include cigarette smoke, silica dust, and certain viruses and bacteria.

Source: http://www.mayoclinic.org/diseases-conditions/rheumatoid-arthritis/expert-answers/who-gets-rheumatoid-arthritis/faq-20091028/