Secondary pharmacodynamic and pharmacogenomic endpoints are 1. Longitudinal evaluation of peripheral lymphocyte subsets prior to and at 1, 4, and 12 months after liver transplantation. This will establish the pattern of lymphocyte reconstitution after depletion with rATG. 2. Inheritance disequilibrium of 100,000 single nucleotide polymorphisms in the major histocompatibility region. This will entail pre-transplant characterization of these single-nucleotide polymorphisms (SNPs) in all children and their biological parents. Preliminary studies lead us to expect identification of outcome-specific patterns of inheritance of SNPs. Such patterns could be used in future studies to allocate appropriate treatment to children based on predicted risk of rejection. For example, the predicted rejector could receive steroids with rATG+Tacrolimus, while the non-rejector could avoid steroids completely.