The download button opens the iTunes App Store, where you
may continue the download process. You must have iTunes installed with an
active iTunes account in order to download and install the software. This
download may not be available in some countries.
From The Hospital for Sick Children:
Biliary atresia (BA) is a chronic liver disease affecting children. LearnAboutBA is a useful learning and teaching app for parents, patients and health-care providers. Featuring two levels of information, users can learn at their own pace. This app helps users understand all aspects of biliary atresia from anatomy to treatment using beautiful illustrations and animations.