We don’t know the cause of rheumatoid arthritis. We certainly know there’s a genetic piece to it. There are certain genetic previous positions that have been identified but they don’t necessarily cause rheumatoid arthritis. We know that smoking actually do not specifically a cause of rheumatoid arthritis and everybody is associated with rheumatoid arthritis. So people with rheumatoid arthritis are for more like to be smokers then someone else without rheumatoid arthritis. Other things have been proposed but frankly at this point we don’t really know the underline root caused.