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Mysteries
Of Medical Genetics Solved Using Punnett Square
Screening for diabetes, hypertension to be simplified
BETHESDA,
MD--Researchers at the National Institutes Of Health (NIH) have discovered
a brand new indication for an age-old device - the Punnett Square.
In lieu of
costly universal screening programs for such diseases as diabetes, hypertension,
and colon cancer, scientists now believe that simple Punnett Square analysis
can accurately predict which individuals are likely to develop certain
conditions, thereby allowing selective screening in these individuals.
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Reginald
C. Punnett, inventor of the Punnett Square
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"The
Punnett Square is an amazing tool that's been terribly overlooked for
all-too-many years," said Dr. Jeffrey Maynor, a geneticist at the
NIH. "But what we've discovered is that, well, what works for peas,
works just fine for humans too."
Maynor and
his colleagues argue that Punnett Square analysis is simple and inexpensive,
and involves only seconds of a physician's time, making it "the ideal
screening tool for today's managed care environment."
The Punnett
Square has been used for decades to demonstrate inheritance of traits
in normal and wild-type peas and other legumes.
For example,
the offspring of two pea plants, one of which is heterozygous for the
dominant "tall" gene (Tt), the other of which is homozygous
for the recessive "short" gene (tt), can be depicted
thusly:
Therefore,
50% of the pea plant offspring will be tall, and 50% will be short.
"Let's
say you're seeing a patient for the first time in the office," says
Maynor. "Should you screen for, let's say, diabetes? Easy. Ask the
patient whether either parent had diabetes. Then, put the information
into the Punnett Square."
"For
example, say one parent has diabetes, and the genotype happens to be DD.
The other parent doesn't, so their genotype is dd. So the Punnett
Square looks like this:
"Clearly,
this patient has a 100% chance of developing diabetes! They should definitely
be tested, and treated accordingly."
According
to Maynor, the technique is useful in the screening of diabetes, hypertension,
prostate cancer, colon cancer, breast cancer, pneumonia, and a panoply
of viral gastroenteritides.
Approval
from the FDA is pending.
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