After four years of seeing daughter Aliannah's developmental delays, Teen Mom 2 star Leah Messer-Calvert has finally been given a devastating diagnosis.

Opening up exclusively for the first time to In Touch Leah reveals that her daughter has a rare — and incurable form — of muscular dystrophy.

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“We were scared because we didn’t know what her future was going to look like, but we always pushed for answers,”  Leah, whose story will unfold on the new season of the MTV reality show, tells In Touch. “We never gave up, and we never will. We’ll do everything we can to make sure Ali has the life that she needs.”

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Despite the comfort of a diagnosis, Leah and Ali are still facing unimaginable challenges. “The disorder affects her respiratory system and progresses the older she gets,” Leah explains. “The bigger she gets and the more weight she gains, the harder it’ll be for her muscles to carry the weight.” Which means that even though she’s walking now, Ali will eventually have to use a wheelchair. To prepare, Leah and husband Jeremy Calvert, 24, a pipeline engineer, are planning to sell their recently purchased dream house and move to a more handicap accessible home.

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Though a preview for the new season of the show reveals Jeremy threatens divorce during an intense argument, Leah explains this has only made her relationship with Jeremy stronger. “This is his first marriage — he’s still learning you can’t throw that word around,” she explains. “We both know we’d never get a divorce. Both of us are too happy.”

And even Leah’s ex-husband Corey Simms, 24, and the father to Ali and twin sister Aleeah become a source of support following the diagnosis. “Ali’s condition has brought us all extremely close together,”  she tells In Touch. “We have to stay strong for Ali, and things are going good.”

Tune in to the premiere of Teen Mom 2, on Jan. 21 at 10 PM on MTV.

For more, pick up the latest issue of In Touch, on newsstands tomorrow.

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