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Scientists learn more about genetics of AIDS (10-11-98)

Studies to be published Tuesday (Oct. 12) in the Proceedings of the National Academy of Sciences reveal significantly more details about why some individuals infected with the AIDS virus grow sick within months, while others go years without noticeable symptoms.

The studies, conducted at The University of Texas Health Science Center at San Antonio in collaboration with other institutions, spotlight gene variations in molecules that influence an individual's susceptibility to AIDS progression. The molecules in which these genetic variations were found play a critical role in the entry of the AIDS virus into cellular portals called "co-receptors."

"One of the most startling aspects of the studies is that they have provided further evidence that the spectrum of gene variants associated with disease acceleration or retardation differs between African Americans and Caucasians," said study leader Sunil K. Ahuja, M.D., associate professor of medicine at the Health Science Center.

The study looked for co-receptor gene variants in 2,300 people--half with HIV infection and half without. The scientists found combinations that retarded HIV-1 disease in African Americans and others that retarded it in Caucasians. "Such combinations of alleles (gene variants) may have offered selective advantages to ancestral Caucasian and African populations who were exposed to different spectrums of disease-causing agents," Dr. Ahuja said.

Dr. Ahuja likened these combinations to genetic "ZIP codes" that in the future could be used to assess a person's AIDS susceptibility. Treatments could also result.

Of the 1,151 HIV-positive patients evaluated, 54 percent were Caucasian, 37 percent were African American, 6 percent were Hispanic and 3 percent were of other origin. The 1,199 uninfected individuals represented ethnic groups living in Africa, Asia and Europe. Ninety-four percent of the subjects were male.

During the study, 38 percent of HIV-infected individuals progressed to AIDS and 34 percent died. The researchers correlated these outcomes with the genetic analysis.

AIDS incidence in this country is changing. The disease once predominantly affected homosexual Caucasian men but now largely strikes minority groups. "Non-Hispanic blacks and Hispanics accounted for 47 percent and 20 percent, respectively, of persons diagnosed with AIDS in 1997, the highest proportions thus far in the epidemic," according to a report summary from the U.S. Centers for Disease Control and Prevention.

This trend makes the study of population-specific genetic determinants "compelling," the authors wrote.

The study was conducted in close collaboration with Lt. Col. Matthew Dolan of the Infectious Diseases Service at Wilford Hall Medical Center in San Antonio. Wilford Hall is the referral hospital for all Air Force personnel who develop HIV infection. Other study collaborators are with the South Texas Veterans Health Care System, Brooke Army Medical Center in San Antonio, the University of Utah, Wake Forest University School of Medicine, the Public Health Research Institute in New York and the Henry M. Jackson Foundation.

The R. J. Kleberg Jr. and H. C. Kleberg Foundation, the U.S. Department of Veterans Affairs, the National Institutes of Health and the National Science Foundation provided grant funding.

The paper was edited by Anthony S. Fauci, M.D., director of the National Institute of Allergy and Infectious Diseases.

Reporters: You may acquire a copy of the scientific paper from the National Academy of Sciences News Office, (202) 334-2138.

Contact: Will Sansom