(Adjective) Acceptable in all references for lesbian, gay, bisexual, and transgender, or lesbian, gay, bisexual, transgender, and questioning and/or queer. In quotations and the formal names of organizations and events, other forms such as LGBTQIA and other variations are also acceptable with the other letters explained. I generally stands for intersex, and A can stand for asexual (a person who doesn’t experience sexual attraction), ally (some activists decry this use of the abbreviation for a person who is not LGBT but who actively supports LGBT communities), or both. Use of LGBT or LGBTQ is best as an adjective and an umbrella term. Don’t use it, for instance, when the group you’re referring to is limited to bisexuals.
(Source: AP Stylebook)