Developing tools for reliable
'gene chip' measurements
sometimes called "gene chip" devices, enable
researchers to monitor the activities of thousands of
genes from a single tissue sample simultaneously, identifying
patterns that may be novel indicators of disease status.
But generating consistent, verifiable results is difficult
because of a lack of standards to validate these analyses,
scientists from the National Institute of Standards
and Technology (NIST) and collaborators warn in the
May 20 online issue of Clinical Chemistry.
Microarrays are keychain-sized devices with as many
as several million tiny spots, each of which examines
genes of interest simultaneously using minute sample
volumes. This highly sensitive technology is relatively
new, and standard procedures to ensure the reliability
and comparability of results are only beginning to emerge.
For instance, results can change as a result of differences
in how tissues are collected and processed; variations
in how the molecules are counted, attached to substrates
and labeled for detection; deviations from recommended
protocols by lab personnel; and malfunctioning or miscalibrated
equipment. Such variations need to be controlled before
this technology can be used reliably in clinical settings
and in devices requiring regulatory approval, according
to the paper.
As a first step toward addressing reliability issues,
a consortium co-led by NIST and industry is developing
standards that will satisfy needs identified at a 2003
workshop. At the workshop, organized and hosted by NIST,
leaders in the microarray field from industry, government
and universities recommended the development of a well-characterized
set of ribonucleic acid (RNA) molecules whose identity
and concentration are known. RNA is an important product
of gene activity. Users will be able to validate the
results of gene chip analyses by adding such a reference
material to their samples and comparing the measured
values to what would be expected for them. Such a reference
material also will enable technology developers and
researchers to assess the performance of their assays.
The paper was co-authored by scientists from Genomic
Health, Inc., Agilent Technologies, the U.S. Food and
Drug Administration, and The Institute for Genome Research.