In the Longitudinal Study of Ocular Complications in AIDS [22], excess death rates ranged from 128 per 1000 PYRS in individuals who had cytomegalovirus retinitis, a viral load of greater than 400 copies/ml, and a CD4 count of less than 200 cells/mm3, to only 8 per 1000 PYRS for individuals lacking these factors. The gene discussed is CD4; the disease is AIDS.