A reason for her departure has not been given.
She will now be played by Brazil-born Alice Braga, who stars in USA’s “Queen of the South.”
In the comics, Reyes is a Puerto Rican mutant who has the ability to form bio-force fields around her body when attacked.
In the film, she is said to be a mentor of sorts for the young group of mutants, which include Magik (Anya Taylor-Joy), Wolfsbane (Maisie Williams), Sunspot (Henry Zaga), Cannonball (Charlie Heaton) and Dani Moonstar (Blu Hunt).
“Nee Mutants” begins production next month in Boston for a April 13, 2018 theatrical release.