Australasian Science: Australia's authority on science since 1938

A Better Test for Childhood TB

A distinctive genetic “signature” offers new hope for the development of a rapid and affordable diagnostic test for children infected with tuberculosis each year.

The discovery of a genetic expression signature in the blood of children with TB was published in the New England Journal of Medicine by an international consortium of investigators who studied more than 2800 children admitted to hospitals in South Africa, Malawi and Kenya with symptoms of TB.

The researchers found the signature by examining which genes were activated or suppressed in blood samples from African children with a confirmed diagnosis of TB. They compared these patterns to those found in children with other diseases similar to TB, and identified an expression signature of 51 genes indicative of active TB.

Dr Lachlan Coin from The University of Queensland’s Institute for Molecular Bioscience led the statistical analysis that identified the signature. “One of the main challenges was to distinguish TB from other infectious diseases, because the baseline inflammatory response to infection means that the difference in signatures is more subtle than between TB and healthy controls,” Coin said.

“We also wanted to find the smallest number of genes we needed to measure to diagnose active TB. A test that surveys fewer genes costs less. This is an important consideration given the majority of children with TB live in developing nations.”

The next step for the researchers is to turn their findings into an affordable and rapid test for TB that can be used worldwide. Coin also hopes to secure funding to trial the test in Papua New Guinea, where TB is estimated to be the largest cause of infectious disease mortality.

According to the World Health Organisation, TB is second only to HIV/AIDS as the greatest killer worldwide due to a single infectious agent.