Researchers have identified a human gene that causes some HIV-infected people taking protease inhibitors to experience a dangerous rise in cholesterol, Reuters Health reports. Patients who have a small genetic variation in the cholesterol-regulating gene known as SREBP-1ca single nucleotide switch among the several million that make up DNA strandsare significantly less likely to develop elevated cholesterol levels than those without the variation. Two copies of the SREBP-1c gene are inherited from each parent, and only a variation in both copies seems to protect against the drug-induced cholesterol increases. About 30% of patients taking protease inhibitors do not experience elevated cholesterol levels, researchers said. This nearly matches the estimated 25% of the population at large that carry the double-gene variation. Researchers suggest that testing for this genetic variation prior to antiretroviral treatment may help doctors identify which of their HIV-positive patients are likely to develop potentially serious protease inhibitorrelated cholesterol problems.