What does it mean for
health care?
The best current examples of
molecular medicine exist in laboratory
medicine—
that
branch of medicine concerned with
examination of body fluids and tissues in
order to establish and verify a diagnosis.
(Some call the pathologist, the physician
involved in diagnostic examination of fluids
and tissues, the “doctor’s doctor.”)
Pathology and laboratory medicine are
mainstays of the clinical “workup” of a
patient, and establishing "medical necesity."
Over the
decades, many branches of pathology have
evolved to deal with different conditions.
Blood may be examined for protein factors to
diagnose a clot, red blood cell number to
diagnose anemia, white blood cell number to
diagnose leukemia, cholesterol and other
lipids for cardiovascular disease risk;
there are literally hundreds more examples.
In the
1980s, scientists discovered that certain
questions about disease could be answered by
examining a patient’s DNA
and RNA. The
DNA of blood and
bone marrow could be examined to identify
key markers of leukemia or lymphoma. Blood
cell DNA could be
examined for genetic mutations indicative of
sickle cell anemia.
These were
examples of the new field of molecular
diagnostics; many of the first tests in the
field were for diseases of the blood, since
blood is such a readily accessible tissue.
In time, we learned how to test solid tissue
for DNA changes
associated with solid tumors and bodily
fluids for specific infectious diseases, for
example urine for Chlamydia and plasma for
HIV.
Molecular
diagnostics grew in the ‘90s and into this
century. At the same time, great scientific
progress led to the sequencing of the
complete human genome. An age of molecular
medicine where science had now deciphered
the blueprint of life was able to take full
advantage of the maturing field of
DNA and
RNA diagnostics,
also referred to as molecular diagnostics.
How can this work
impact treatment and outcomes?
A prime
example of molecular diagnostics meeting
personalized therapies includes the
diagnosis and treatment of a particular form
of leukemia.
In chronic
myelogenous leukemia (CML), a highly
specific change at the
DNA level triggers and sustains the
disease. Molecular pathologists have been
able to diagnose that specific molecular
change since the early ‘90s. In time a drug
was developed that worked to shut down this
process. The molecular change pathologists
had been diagnosing for years led to a
medication designed to defeat that
particular molecular change; this is a case
of molecular diagnostics meeting tailored
treatment of a tumor—a prime example of the
benefits of molecular medicine.
What is personalized
medicine?
Personalized
medicine takes into account that each of us
is different, particularly when it comes to
our DNA and the
way each of us may respond differently to
similar treatments for the same disease.
Physician-directed use of personalized
medicine is starting to facilitate the
effective, tailored treatments of patients.
Personalized medicine depends upon molecular
analysis, that is, laboratory tests that
analyze a patient’s DNA,
RNA and/or protein patterns.
American
(allopathic) medicine is concerned with
management of a patient’s disease or
predisposition to disease. Personalized
medicine takes the goal of optimal
management one step further by choosing
approaches most likely to be successful in
the context of a patient’s genetic and
environmental profile.
Given that
our genes define every characteristic of a
person, to a greater or lesser extent and
depending on environmental factors, it’s
actually not surprising to consider that our
genetics influence our ability to respond or
not respond to drugs. Just as allergic
reaction to ragweed pollen is genetically
determined (it bothers some and not others),
so too is the ability or inability to
metabolize specific foods or prescription
drugs.
What is
Pharmacogenomics?
Pharmacogenomics, or PGx, is the response to
therapeutic drugs by an individual as a
function of that individual’s genetic
makeup.
processes
take place at a molecular level in recent years.
This has been exemplified most notably by the
sequencing of the human genome. These developments
are continuing at an explosive pace and with them
comes an ever sharper focus on the essential
molecular mechanisms underlying the normal
functioning of cells, tissues and organisms
themselves.