In the case of HIV-positive recipients of liver transplants, there is evidence that using a CD4+ threshold ≥ 100 cells/μL is safe provided there is no history of any opportunistic infection or malignancy (in which case a CD4+ threshold of 200 cells/μL is recommended).41 Another exception to the rule would be immune non-responders, who fail to reconstitute an adequate CD4+ count despite prolonged viral suppression, but this requires consultation with an infectious diseases specialist on a case-by-case basis. This evidence concerns the gene CD4 and infectious disease.