There are seven different types of Juvenile Idiopathic Arthritis..  It is uncommon for most forms of JIA to occur in siblings; children who present with the type of JIA referred to as ERA (Enthesitis Related Arthritis ; enthesitis refers to inflammation where ligaments and tendons insert onto bone), which tends to occur in older children and is more common in boy, are more likely than other JIA subtypes be found in siblings.  In children with the type of JIA referred to as oligoarticular JIA (children with fewer than 5 joints involved; the word “oligo” comes from the Greek word meaning “few”) are the most likely to have uveitis that is chronic and generally not associated with symptoms such as redness of the eyes or eye pain . Oligoarticular JIA occurs uncommonly in siblings but it can occur. The occurrence of oligoarticular JIA with associated uveitis is even more rare but again it can occur. The type of uveitis associated with ERA tends to be associated with symptoms and intermittent brief courses; this type of arthritis is thought to be somewhat more likely to occur in siblings with the ERA type of JIA but the occurrence is still uncommon.  The fact that JIA and JIA with uveitis can occur in siblings, although rarely, suggest the possibility of a genetic influence on the occurrence of the disease or an environmental exposure or, perhaps more likely,  an interaction of genes with the environment.  More research is required to answer this important question.  Because JIA and JIA with uveitis occur rarely in siblings,  international research collaboration, such as that which is being led by Canadian pediatric rheumatologists and ophthalmologists, will be important to help answer this question more thoroughly.