One problem with Marvel's Cinematic Universe is they can't include 'mutants' by name as 20th Century Fox holds those rights - even for the non-"X-Men" mutants.
In the comics, the concept of 'Inhumans' is taking precedence - to the point that many suspect Marvels mutant characters, such as Quicksilver and Scarlet Witch in the upcoming "Avengers: Age of Ultron", will be renamed 'inhumans' in the upcoming films.
Asked about this by The Huffington Post, Marvel Studios president Kevin Feige says:
As it relates to Scarlet Witch and Quicksilver? No. No, no, no. Inhumans is something that we are definitely thinking about and we think there’s great potential there for a great movie. But, no, no — we have not linked those two [concepts]."