Mysteries Of Medical Genetics Solved Using Punnett Square

March 7, 2001

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.

Reginald C. Punnett,
inventor of the
Punnett Square

"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.

Remember: Quality Without The Q Is Just Uality!