For two years, a bunch of medical geneticists in Maryland and New Jersey sifted through 1,000 different genetic mutations. They looked for cellular changes that are fatal and ones that are treatable. They argued. Eventually, they decided to include close to 600 mutations found in more than 160 diseases in a single genetic screening test that will be available come January.
GenPath Women’s Health, part of N.J.-based Bio-Reference Laboratories, announced the new development on Thursday at a meeting of the National Society of Genetic Counselors. GenPath says it is the most comprehensive screen currently offered: in a field of rare diseases, the test distinguishes itself by scanning for 95 disorders that are not screened for by any other company, including obscure tongue-twisters such as 3-hydroxy-3-methylglutaryl-CoA lyase deficiency and cerebrotendinous xanthomatosis.
Company officials put a lot of thought into a name for the test, ultimately deciding to call it the Pan-Ethnic Carrier Screen as a way to signal to all women, regardless of ethnicity, that genetic-testing is important for them.
But do all women really need to undergo genetic testing? More than half of pregnant women do some kind of prenatal screening or testing of their fetus, but there aren’t readily available numbers on how many women choose to learn if they’re carriers for various genetic diseases. The vast majority of women undergo carrier screening based on their ethnic background, although many, regardless of their heritage, are also screened for cystic fibrosis. Traditionally, certain ethnic groups — especially Ashkenazic Jews of Eastern European descent — have been advised to consider carrier screening for various fatal conditions including Tay-Sachs and Canavan diseases.
Indeed, GenPath is presenting the new test as a way to level the genetic playing field and expand testing to any woman, anywhere. “There are a good number of ethnicities that have been ignored by genetic testing,” says Marc Grodman, CEO of Bio-Reference. “You don’t have to be Jewish to have a genetic test. That’s why we are calling this a ‘pan-ethnic’ screen.”
In general, say genetic counselors, increased interest in genetic testing is welcome because it encourages women to better understand how their genetic makeup could impact their children. But pregnant women are getting bombarded with options: this is just the latest of a battery of new blood tests that can determine everything from fetal sex to Down syndrome to paternity.
When it comes to genetic testing, in particular, it’s important to make sure that any screening is done in conjunction with a genetic counselor who can explain results, review options and offer guidance. “Sometimes that means not testing because the patient would not benefit or is not interested once they have a thorough understanding of the test, the benefits and possible limitations,” wrote Karin Dent, president of the National Society of Genetic Counselors, in an email.
The GenPath test will be marketed to physicians, who will then offer it to their patients. It will cost $500 out-of-pocket should insurance companies decline to pay. Ideally, women would be tested before they get pregnant. Should they turn up positive for a mutation, their partner would need to be tested too. If they’re both positive for the same mutation, they would have a 25% chance of having an affected baby.
GenPath is not the only company working on new prenatal genetic tests. Good Start Genetics of Cambridge, Mass., is initially targeting fertility clinics with its DNA-sequencing test that will allow detection of a larger spectrum of mutations than the current genotyping method. Its cystic fibrosis screen, for example, is more sensitive than any test currently on the market, says Greg Porreca, the start-up’s co-founder.
Its test, which should be available sometime next year, will look for about 20 conditions recommended by the American Congress of Obstetricians and Gynecologists (ACOG) and the American College of Medical Genetics. GenPath’s test, on the other hand, has the potential to identify a host of additional diseases: 3-Hydroxy-3-Methylglutaryl CoA lyase deficiency, for example, is diagnosed when a person can’t process an amino acid called leucine. Potentially fatal if untreated, the condition is so uncommon that it’s been reported in fewer than 100 people worldwide.
ACOG officials declined to comment on GenPath’s test, but its 2008 policy statement advises screening or testing “for a limited number of severe child-onset diseases.” The American Pregnancy Association, meanwhile, expressed skepticism about the wide net that GenPath is casting. “Genetic testing historically is only recommended for those identified as at risk,” says Brad Imler, the group’s president. “We would advise testing because there is a reason to test, not just a hypothetical something-could-be-wrong.”
But knowledge is power, argues Grodman, who is convinced that parents would want to know ahead of time about any increased risks in order to be prepared. “The biggest fear about rare disorders is that a baby is born and no one can make a diagnosis,” says Grodman. “Just because it’s a hard decision and a hard process doesn’t mean we should shy away from asking the questions.”