This registry was created to develop a comprehensive databank of individuals with Alagille syndrome (ALGS) to better understand its characteristics, determine areas needing further research, and develop targeted treatments to improve the lives of those affected. Everyone with ALGS, regardless of age, severity of symptoms, affected organs, place of residence, etc., is eligible to participate. The only way to unravel the mystery of ALGS is through research. Research needs data, and that information comes from those willing to share their time, family history, and samples (tissue, blood, DNA, etc.).