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What is selective mutism? Girls help sister to communicate

15 February 2016 Last updated at 07:13 GMT

Casey, Hannah and Lucy love spending time together and having fun like a lot of sisters. But Hannah has a condition called selective mutism, which means that the only people she speaks to are her family.

Hannah's condition means that she gets worried and anxious speaking in certain places like in public or at school.

Hannah says that she would like to talk, but her selective mutism makes it feel like the words get stuck.

Luckily, Hannah has her sisters Casey and Lucy who she can rely on to help her communicate, and explain why she isn't talking if people don't understand.

Casey and Lucy hope that Hannah will be able to talk to everyone in the future, but they are happy to wait until she is ready.