title: Reply.
authors.affiliation: University of Pennsylvania Perelman School of Medicine and Children's, Hospital of Philadelphia, Philadelphia, PA.
authors.forename: Pamela F
authors.initials: PF
authors.lastname: Weiss
authors.affiliation: National Institute of Arthritis Musculoskeletal and Skin Diseases/NIH, Bethesda, MD.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Colbert