Why do some HIV-positive people develop AIDS soon after infection, while others can stay disease-free for more than 20 years without treatment? Around 25 key genes have already been unearthed, but few are so influential as those studied by Mary Carrington at the National Cancer Institute in Frederick, Maryland, and her team.
They looked at two genes that regulate natural killer (NK) cells – a primary line of defence against invading viruses. Each gene exists in many variations, and each combination confers different protection. Less than a third of those with the most protective combination develop AIDS nine years after…
