The Genetics of Rheumatoid Arthritis

Researchers have identified several disease features that are common among people with rheumatoid arthritis (RA) who are related.

A report on their findings appears in the March issue of Arthritis and Rheumatism.

The results point to certain genetic factors that influence susceptibility to the disease and its progression. The findings could help scientists identify new markers for prognosis in people with RA.

Researchers studied 1,097 siblings from 512 families with multiple cases of RA. The volunteers provided clinical and demographic information, including whether their parents had RA.

The researchers obtained radiographs of the hands and feet of each study subject, tested all of them for rheumatoid factor, and analyzed the subjects against a list of disease symptoms and possible manifestations.

The study found that the presence of serum rheumatoid factors of nodules was strongly correlated among siblings. There was also a significant sibling correlation for age at RA diagnosis and disease severity.

Interestingly, the study found that, regardless of the total number of brothers or sisters in these families, the number of siblings stricken with RA was remarkably consistent -- between two and three.

This finding challenges previous findings that the number of people with RA is higher in larger families.

"We did not observe an increase in the number of affected siblings as total sibship [the amount of children born to a couple] size increased. The striking difference in our results compared with those reported by investigators in The Netherlands indicates the need for further study of this issue," study author Dr. Damini Jawaheer writes.

More information on Rheumatoid Arthritis.