Leah Messer of "Teen Mom 2" may have more on her plate than some of the other moms, but she has taken to Snapchat to show that her elder daughter, Ali, can thrive, even with her disability. The youngster is one of only a few people in the world to suffer from Titin's muscular dystrophy, and it has made growing up a little more challenging for the little girl. Additionally, Ali has been eager to keep up with her rambunctious twin sister, Gracie, who loves to do things like tumble, gymnastics and cheerleading. On a recent episode of "Teen Mom 2," Gracie was seen berating her twin sister for no longer wanting to do gymnastics because it makes her tired.

Ali passes a major milestone

Life hasn't always been easy for Ali, Leah's oldest daughter, due to her limitations with muscular dystrophy. The young girl has had trouble walking and it has made many milestones take longer for her to achieve. According to the show, she has a wheelchair that she uses in case she gets tired in order to preserve her energy, and it is more difficult for her to participate in activities than other children her age. It is anticipated that she may regress as she is older, however, not a lot is known about the disorder because it is so rare.

However, Ali has proved that she can do almost everything everyone else her age can do, even if it takes her just a little bit longer to get there.

This week, Leah Messer proudly showed off her daughter riding a bicycle, which is something she was previously unable to do. The little girl was shown on "Teen Mom 2" as learning to ride a bike with her physical therapist's aid, but it appears that Ali can now ride the bike completely unaided.

Criticism of Leah and Corey's reactions to her disease

Leah Messer shares Ali with her ex-husband, Corey Simms. The pair have been heavily criticized on "Teen Mom 2" discussion sites for not "facing reality" when it comes to the extent of Ali's limitations. Corey was very reluctant to purchase his daughter a wheelchair, even when it became apparent that she needed one in order to play with the kids at school and the doctor recommended it.

He has also been criticized for seemingly thinking that one day Ali will magically get better instead of regress in her muscular dystrophy as the doctor has suggested. However, it is worth noting that this kind of news would be difficult for any parent to accept, much less one in the public eye whose entire life is on a reality television show.