All 3 Uses of

gender
in
1st to Die, by Patterson

It had been a long, hard time since I had put my trust in anybody whose gender started with an M. Maybe, in a different time ...I was thinking.†
p. 172.3 *

gender = male, female, or any of many trans categories

"Not bad for a collection of gender-impaired public servants," Claire agreed.†
p. 317.5

There aren't any flashing gender signs in urine, but there are things to look for.†
p. 386.5

Definitions:

(1) (gender as in: gender discrimination)
male or female

or (especially regarding self-identification): the state of being male, female, or in any of many trans categories

While the word sex can almost always be substituted for this meaning of gender, gender is typically used in reference to cultural or social differences, while sex is typically used for biological differences.
(2) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

Less commonly, gender can refer to a grammatical categories. In some languages (not modern English), nouns that are not distinguishable by biological sex, can still have a feminine or masculine gender.