When a patient needs organ transplant they are updated in the list of potential recipients in the data of United Network of Organ Sharing (UNOS). The hospital where the patient is being treated updates medical, genetic, and social information in UNOS record. UNOS shares list of potential donors based on blood type, tissue type, organ size, medical urgency of patient’s illness, time already spend on the waiting list and geographical distance between the donor and recipient. UNOS offers the organ to transplant center of patient and the doctors of patient decide whether the patient’s immune system and body is going to accept or reject the organ. If the team rejects the organ in the favor of their patient, the organ is offered to the next patient for which the respective transplant center is contacts.