One of every three genetic tests examined by a team of researchers at the San Diego Naval Medical Center shouldn’t have been prescribed, a finding that adds to a growing body of evidence suggesting that genetic tests are routinely overused and often misinterpreted.

The new analysis earned a first-place award from the American Congress of Gynecologists and Obstetricians, which held its national meeting in San Diego this week.

Though the study’s scope was limited — it reviewed 114 cases and looked at only seven genetic tests among the hundreds that doctors regularly order — its results nonetheless reinforce previous research that arrived at similar conclusions.

In 2014, for example, Stanford University reported that three women in the San Francisco Bay Area chose abortions after undergoing DNA screenings that erroneously showed their unborn babies had a serious genetic issue such as Down syndrome or the nearly always fatal genetic condition Trisomy 13.


Recently, many researchers have criticized physicians who recommend bilateral mastectomies for women receiving the finding of “uncertain significance” when they undergo genetic testing for mutations of the BRCA 1 and 2 breast-cancer genes.

“This underlines that informed decision-making is very important,” said Dr. Kathleen Ruzzo at the naval medical center. She is the main recipient of the OB/GYN organization’s first-place honor.

Genetic testing has played a growing role in health care since doctors began screening newborns for phenylketonuria, often called PKU, in 1963 using a blood sample taken from each baby’s heel. Early detection allowed doctors to prevent a build-up of amino acids in the bloodstream that could lead to brain damage.

Many more genetic tests have been added in the ensuing decades. In particular, full sequencing of the human genome in 2003 has led to a proliferation of such tests, which try to look for everything from Alzheimer’s and Parkinson’s diseases to colorectal cancer.


The San Diego naval team found that in 44 of the cases it evaluated — 38 percent — health care providers used genetic tests in ways that were not fully compliant with best-practice guidelines issued by organizations such as the American Congress of Gynecologists and Obstetricians.

Twenty-four of the tests were prescribed to help diagnose symptoms they actually were not designed to explain, 12 provided inadequate information for diagnosing specific symptoms and eight gave false reassurance about genetic risk.

Dr. Monica Lutgendorf, another OB/GYN on the San Diego naval research team, noted that one commonly ordered genetic screener, called a free cell DNA test, is significantly pricier than the blood serum test it replaces.

“It costs between $600 and $1,000 compared to the serum screen, which costs about $100,” Lutgendorf said.


The team did a financial analysis of the 44 wrongly ordered tests it discovered and determined that choosing the correct options would have saved a total of nearly $21,000.

What’s more, looking at just the free cell DNA test, both physicians said choosing the serum test for women younger than 35 would not only save money, but also increase the odds of detecting other potentially harmful conditions and would reduce the chance of false-positives for conditions such as Down syndrome.

The San Diego naval researchers said their findings argue for better education of doctors ordering these tests and for greater involvement of genetic counselors, who specialize in understanding the nuances of what these powerful diagnostic tools can do — and cannot do.

The American Congress of Gynecologists and Obstetricians is featuring new training modules designed to help physicians improve their knowledge about genetic screenings.


Mary Freivogel, president of the National Society of Genetic Counselors, applauded that approach. She said the San Diego naval team’s results roughly track with another study, published in the American Journal of Medical Genetics in 2014, that found 26 percent of genetic tests were wrongly ordered.

Freivogel also said there are plenty of doctors who understand every aspect of the genetic tests they order, but that a significant number do not. Medical schools may not spend much time on the ins and outs of genetic testing, and some students may have attended medical school before the current array of tests were invented.

Doctors are often faced with sales pitches on these tests, which can gloss over key issues, Freivogel said.

Consider the free cell DNA tests, for example. They can predict the risk of Down syndrome with 99 percent certainty. However, risk of disease is not the same as actually having that disease. Screening for risk is not the same as making a definitive medical diagnosis.


“This is a screening test, and it should always be confirmed by an invasive test, such as through amniocentesis, to make sure,” Freivogel said.

She said patients would do well to be thorough and methodical about genetic testing.

“The truth is, it is a unique thing to be able to do this well and to be able to take the time to do it well. If you are going to make an important decision based on genetic test results and you haven’t seen a genetic counselor, I would encourage you to do so first,” Freivogel said.

The National Society of Genetic Counselors maintains a list of counselors at www.findageneticcounselor.com that can be searched by ZIP code.


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paul.sisson@sduniontribune.com


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