Havalah has a disease called Biliary Atresia. Nobody knows what causes Biliary Atresia, but it only happens to newborns and occurs at a rate of 1 in 16,000. The disease basically involves a lack of bile ducts inside the liver, outside the liver, or both. Without bile ducts, toxins build up inside the liver and cause progressive damage until the liver can no longer function.
You can learn more about Biliary Atresia here
You can get a brief synopsis of Havalah's medical history here
Biliary Atresia is the main cause of pediatric transplants. To read more about liver transplants see the following links: