Scientists identify genomic marker for tuberculosis

Scientists have found a genomic marker for TB to identify those under the risk of disease.

Washington: Using a new blood-profiling
technique, American scientists have found a genomic marker for
tuberculosis which they say could help identify who are at the
risk of developing the disease.

Caused by the bacterium Mycobacterium tuberculosis, the
disease usually attacks the lungs and can be fatal if not
treated properly. With current tests unable to identify which
individuals will develop it, the disease still remains an
epidemic in much of the world.

But, researchers at the Nationwide Children`s Hospital in
Ohio, said though a new blood profiling technique, they have
identified the genomic marker which is extremely efficient at
gagging the risks of developing the disease.

Octavio Ramilo, chief of Infectious Diseases at
Nationwide Children`s Hospital, said though tools have been
developed to diagnose infections like TB, they are still not
capable to predict how a person is going to react to the

"It`s difficult to predict patient outcomes, and this is
a real problem," said Dr Ramilo, lead author of the study,
which is published in the journal Nature.

To combat this problem, Dr Ramilo and co-researcher
Asuncion Mejias, used micrography technology to develop blood
profiles in patients specific to infectious diseases.

According to scientists, each infectious agent, be it a
virus or a bacterium, interacts with human immune cells in
unique ways by triggering proteins on white blood cells.

"We can identify patterns among the white blood cell`s
activated proteins and identify a unique `signature` for each
infectious agent," said Dr Mejias.

"This technology allows us to see the whole picture of
infection using a single blood sample, which is a really
powerful tool for the clinic."

For their study, the researchers examined and compared
blood drawn from patients who had active TB, latent TB (which
is not symptomatic or contagious) or who did not have TB.
The team developed genome-wide transcriptional profiles
for each of the patients and discovered a distinct
characteristic, or "signature," of the blood from patients
with active TB. X-rays of patients with this signature were
consistent with signs of active TB.

"The study shows for the first time that the
transcriptional signature in blood correlates with extent of
disease in active TB patients," said Dr Ramilo.

"It validates the idea that this transcriptional
signature is an accurate marker of TB infection."

The team also found that a subset of latent TB patients
had signatures similar to those in active TB patients.
"The signature of active TB, which was observed in 10 to
20 per cent of latent TB patients, may identify those
individuals who will develop disease, but longitudinal studies
are needed to assess this," said Dr Ramilo.

The transcriptional signature was diminished in active TB
patients after two months and completely extinguished by 12
months after treatment.
"These findings suggest that the blood transcriptional
signature of active TB patients could be used to monitor how
well a patient`s treatment is working," said Dr Ramilo.

Ramilo said the new technique holds tremendous potential
and could save numerous lives worldwide.


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