In the article by Manno et al entitled "AAV-mediated factorIX gene transfer to skeletal muscle in patients with severehemophilia B," which appeared in the April 15, 2003, issueof Blood (Volume 101:2963-2972), the second sentence of "Safetystudies" should have read "Vector sequences were detected inthe urine of subjects B and F up to 24 hours after injectionbut not thereafter."