transgender vs transgendered

transgender is not a noun while transgendered is a noun.

Word	Noun	Adjective	Verb	Adverb
transgender	No	Yes	No	No
transgendered	Yes	Yes	No	No

As adjectives, transgender and transgendered are synonyms defined as:

transgender and transgendered: involving a partial or full reversal of gender

transgender (noun)	transgendered (noun)
	a person who has undergone a sex change operation

transgender (adjective)	transgendered (adjective)
involving a partial or full reversal of gender	involving a partial or full reversal of gender