Teen Mom 2’s fifth season debuted on MTV on Tuesday night, and the episode revealed what viewers have been waiting for since the first season. Leah Calvert revealed the rare disease her daughter Aliannah has, which she has been trying to find out since she was just months old.

The now-4-year-old has a rare form of a condition called muscular dystrophy, which will progress as her muscles develop and she gets older. She will eventually need to use a wheelchair as the disease worsens with age.

Calvert, 21, told Us Weekly of her daughter’s condition, "Eventually, Ali could be in the chair all the time. But I've never seen her so happy. She chases [twin] Aleeah and doesn't fall down anymore."

“Ali enjoys drawing and Aleeah takes cheerleading lessons,” she said of her twins with Corey Simms. She had a new baby with her husband, Jeremy Calvert, Adalynn, who she calls a “mama's girl.. I can't go out!"

She also told In Touch about Aliannah’s diagnosis, “We were scared because we didn’t know what her future was going to look like, but we always pushed for answers,” adding, “We never gave up, and we never will. We’ll do everything we can to make sure Ali has the life that she needs.”

image: MTV