After a half-dozen pint-sized robots organize genetic material onto plates
and feed it into computers, Peter K. Gregersen, MD, painstakingly mines the
data, hoping to discover the unique genes that make some people more
susceptible to rheumatoid arthritis (RA).
Gregersen, head of the Feinstein Institute’s Robert S. Boas Center for
Genomics and Human Genetics in Manhasset, N.Y., and his team are edging closer
to solving the puzzle. They recently announced the discovery of two new genes
Up to 60% of children with JIA have
oligoarticular arthritis. Of these children, 20% to 30% have symptoms in more than four joints after the first 6 months, so they are said to have extended oligoarticular JIA. The rest of these children continue to
have less than four joints affected over time. This is called persistent oligoarticular JIA.
About 30% of children with JIA have
RF-negative polyarticular JIA. This means they have polyarticular symptoms without an antibody called rheumatoid factor in their blood.
Fewer than 10% of children with JIA have RF-positive polyarticular JIA. This means they have polyarticular symptoms and also have rheumatoid factor in their blood.
About 10% of children with JIA have
About 10% of children have a form of arthritis called enthesitis-related JIA.
Fewer than 10% have psoriatic JIA.
A few children are said to have unclassified JIA. This means that their symptoms and past health do not exactly match any of the other types of JIA.
Juvenile idiopathic arthritis can occur at higher rates among
certain ethnic groups and in some geographic areas. Environmental and genetic
factors are thought to be responsible, though researchers have yet to confirm
Nistala K, et al. (2009). Juvenile idiopathic arthritis. In
GS Firestein et al., eds., Kelley's Textbook of Rheumatology, 8th ed., vol. 2, pp. 1657-1675. Philadelphia: Saunders
Warren RW, et al. (2005). Juvenile idiopathic
arthritis (Juvenile rheumatoid arthritis). In WJ Koopman, LW Moreland, eds.,
Arthritis and Allied Conditions, 15th ed., vol. 1, pp.
1277-1300. Philadelphia: Lippincott Williams and Wilkins.
Primary Medical Reviewer
John Pope, MD - Pediatrics
Specialist Medical Reviewer
Stanford M. Shoor, MD - Rheumatology
June 11, 2010
WebMD Medical Reference from Healthwise
June 11, 2010
This information is not intended to replace the advice of a doctor.
Healthwise disclaims any liability for the decisions you make based on this