One of the editors at one of the pubs I copy edit asked me to research whether it's best used as an adjective (a transgender person), a noun (Chris is a transgender), or whether it's "transgendered."
Webster's New World College Dictionary, which this newspaper group follows, say it's only an adjective and that "transgender" is preferred but "transgendered" is also okay. Merriam-Webster online agrees.
Dictionary.com gives it first billing as a noun but also lists it as an adjective. Plus it allows "transgendered."
American Heritage (via Dictionary.com) doesn't allow the spelling "transgender." It's "transgendered," say they, and it's only an adjective.
Causes June Casagrande Supports
Planned Parenthood, ClimateCrisis.net, the Richard Dawkins Foundation, Pet Orphans of Southern California, KIVA