When transplant surgeon Dinee Simpson sits in a consultation room with a patient, often they’re joined by the patient’s spouse or children or both. Sometimes a meeting includes a patient’s cousins or siblings or friends — anyone who will weave together the fabric of support that patient will rely on when he or she receives a new kidney or liver or pancreas. And sometimes, particularly if the patient is black, more than a century of mistrust of the medical community also joins them in the room.