(^12) Upfront
Kaposi’s sarcoma (KS) presents a
diagnostic challenge at the best of times:
the disease can form masses in the skin,
lymph nodes or elsewhere; lesions can
be limited or widespread; they may be
flat or raised; and each of the disease’s
four subtypes may resemble a range
of other conditions. Nevertheless,
conclusive diagnosis is
important, not only for
treatment purposes,
but also because KS
is considered AIDS-
defining, meaning
that its presence in an
HIV-positive patient
makes the diagnosis
of AIDS official.
But histopathologic
diagnosis – the standard
approach – is not always
possible in resource-limited
settings, such as sub-Saharan Africa,
where KS is endemic, and so KS
is often diagnosed through
macroscopic observation.
U n f o r t u n a t e l y , t h e
disease’s heterogeneous
nature means that
clinical diagnosis is
error prone.
It’s clear that a point-
of-care testing device
capable of circumventing the
need for traditional testing would
be invaluable. And so, a team of
engineers, pathologists, dermatologists
and clinical epidemiologists at Cornell
University designed device that can be
operated without electricity: the Tiny
Isothermal Nucleic acid quantification
sYstem – TINY, for short (1).
Jeffrey Martin, Professor of
Epidemiology and Biostatistics at
the University of California, San
Francisco, helped determine
the suitability and accuracy
of the device. He explains
the testing process: “A
small biopsy of the
affected skin is taken
under local anesthetic.
DNA is then extracted
from the biopsy and tested
for the presence of Kaposi’s
sarcoma-associated herpesvirus
(KSHV) DNA via a reaction known as
loop-mediated isothermal amplification
(LAMP).” Because LAMP needs
samples to be heated 154°C, the assay
cannot typically be conducted without
a power source; what makes TINY
unique is its ability to collect and store
heat from any source, including the
sun and Bunsen burners, allowing it
to function without a reliable source
of electricity.
Martin is currently working
alongside colleagues to test the
device’s accuracy across a broad range
of conditions in Africa. At the same
time, the team is establishing demand
for TINY and seeking ways to keep
its cost low. “Obviously, we need to
make this as inexpensive as possible,”
says Martin. “There is little point on
working on such a project if we cannot
make it affordable.”
References
- R Snodgrass et al., “A portable device for
nucleic acid quantification powered by
sunlight, a flame or electricity”, Nat Biomed
Eng, 2, 657–665 (2018).
One TINY Step
at a Time
How to diagnose Kaposi’s
sarcoma in areas without
reliable infrastructure
First author Ryan Snodgrass uses sunlight to heat TINY at the AIDS Healthcare Foundation-
Uganda Cares Clinic, Masaka, Uganda.