There are two principal purposes of this study: 1) to determine whether it is more beneficial for a liver transplant recipient candidate to pursue a living donor liver transplant (LDLT) or wait for a deceased donor liver transplant (DDLT), and 2) to study the impact of liver donation on the donor's health and quality of life.

Adult to adult living donor liver transplantation (LDLT) is a relatively new procedure increasingly used at major transplantation centers. Relatively small numbers of cases are performed at any one center and approaches to the patient and donor are too diverse across centers to provide reliable and generalizable information on donor and recipient outcomes from individual centers. Therefore, a network of nine leading liver transplantation centers and a data coordination center (DCC) has been organized to accrue and follow sufficient numbers of patients being considered for and undergoing LDLT to provide generalizable results from adequately powered studies. This network has established the Adult to Adult Living Donor Liver Transplantation Cohort Study (A2ALL) that will conduct both retrospective and prospective studies of LDLT.

The primary study objective is to analyze the effect of choosing to pursue living liver donation. The principal hypothesis is that pursuit of a living liver allograft leads to decreased pre-transplant morbidity and mortality and better long term outcomes for patients starting from the point at which listed patients have a potential donor evaluated (at least a history and physical examination). Emerging data suggest that LDLT provides an inferior graft because of reduced parenchymal mass and added technical complexity when compared to a whole liver used for DDLT. The magnitude of the disadvantage to the LDLT graft will be assessed by comparing results between LDLT and DDLT from the time of transplant. Finally, a careful and detailed series of studies of potential and actual living liver donors is included as a primary objective because of the tremendous importance of this issue to our understanding of the impact of the procedure.

Secondary objectives will address selected biological and clinical issues in transplantation structured around the comparison between DDLT and LDLT.

Inclusion Criteria - Potential Recipients:

• Potential recipient listed for single organ (liver) transplantation
• Patient is eligible for LDLT
• Age ≥ 18 years old at the time of donor history and physical exam
• Indication for transplant: non-fulminant liver disease
• Potential donor scheduled for evaluation (history and physical examination) within four weeks

Inclusion Criteria - Potential Donors:

• Meet donor criteria of the transplant center
• Age >= 18 years old at donation
• Be evaluated with a history and physical examination at the transplant center
• Potential donor's recipient listed for single organ (liver) transplantation

Potential recipients and donors for transplantation will be evaluated and invited to participate in the study if they are eligible for LDLT using standard criteria for this procedure according to the practice of the transplant center.