New blood test predicts onset of TB up to two years in advance

A new blood test has been found to more accurately predict the development of tuberculosis up to two years before its onset in people living with someone with active Tuberculosis (TB), according to research published online in the American Journal of Respiratory and Critical Care Medicine, an American Thoracic Society journal.

Those living with someone with active TB are at highest risk for developing the disease, yet only about 5-20 percent of people infected with tuberculosis actually develop TB.

A blood test that predicts the development of TB without putting large numbers of lower-risk people through unnecessary preventative treatment is not currently available.

In “Four-gene Pan-African Blood Signature Predicts Progression to Tuberculosis,” researchers from an international research consortium report that they developed and validated a blood test that measures the expression levels of four genes that can more accurately predict the development of TB in high-risk patients in Sub-Saharan Africa.

“We found that this prediction [up to two years before the onset of the disease] is possible through measurements of a combination of a four-gene signature in the blood,” said Professor Gerhard Walzl, MMed, PhD, lead study author and leader of the Stellenbosch University Immunology Research Group, Tygerberg, South Africa.

“This signature, known as ‘RISK4,’ was found to be present in all cohorts in the study, from South Africa, Gambia and Ethiopia.” RISK4 is a combination of four genes associated with inflammatory responses.

For quality control, the scientists used a training-test set approach: they divided the sample data up in a discovery (training) set on which the signature was developed and then tested the signature on the remainder of the samples (test set) in a blinded manner.