by Dr. Hsien-Hsien Lei
Posted September 29, 2008 in DNA Testing, Personalities with DNA
Of all the direct-to-consumer genetic tests currently available to the public, early gender DNA tests are among the most controversial. The test allows pregnant women to submit finger prick blood samples which the lab screens for the presence of Y-chromosomal DNA from the fetus; Y-chromosomal DNA positive indicates a boy, negative indicates a girl.
Karen Kaplan of the LA Times looked into the accuracy of gender DNA test kits in February of this year. And a lively discussion among Eye on DNA readers follows my post: Is the Pink or Blue early baby gender DNA test accurate? One of the commenters is Terry Carmichael, VP of Marketing & Sales at Consumer Genetics, manufacturer of The Pink or Blue Early DNA Gender Test.
Terry is the founder of Gene Tree DNA Testing Center which was sold to Sorenson Genomics in 2001. He also helped launch at-home DNA paternity DNA tests in major U.S. drugstores in 2007 (see previous Eye on DNA post). I was impressed with Terry’s openness and invited him for an email interview.
Hsien: What is your company’s motivation for providing an early gender DNA test direct to consumers?
Terry: Trying to predict the sex of a baby has been a centuries old game within families. Families want to know the sex of a baby for many reasons. Most want to make an announcement at a family gathering, or surprise their husband with the anticipated gender, or preparing siblings for a new baby boy or girl. Others want to know so that they can prepare siblings that will have to share rooms, or to begin to decorate a room for the baby based on gender. The main motivation for Consumer Genetics is the gratification we get when helping families plan for the future by offering them the information they are seeking to know.
Hsien: Can you tell us more about the quality assurance protocol for the Pink or Blue DNA Gender Test?
Terry: The Pink or Blue test is based on several large scale studies that have scientifically proven the ability to determine gender by detecting Y-chromosomal DNA of fetal origin in a large sample of a mother’s blood (10 ml). The accuracy of this method in a clinical setting has been shown to be between 97.8 to 100% within a population of 1,837 pregnant women. The Pink or Blue test uses the same molecular technique as in the studies (Polymerase Chain Reaction) along with a proprietary method of purifying and amplifying the baby’s Y chromosomal DNA within a much smaller sample of the mother’s blood (usually 60-120 microliters). The company looks for data from the DNA test that shows the baby is a boy. If this data does not show this, then this suggests that the baby is a girl. There are times when the data is not clearly one or the other – imagine a few data points that are on either side of a line. In this case, we report the test as inconclusive. Due to this complex â€œsignal-to-noiseâ€ issue, we regularly run at least 2 tests for each sample to increase the probability of a conclusive result. If all tests are â€œinconclusive,â€ we then ask the customer for a new sample. Therefore, just like ultrasound, we have a portion of samples that we cannot determine gender from, and we have the customer send a new sample for re-testing. This second sample will nearly always give us a conclusive result.
Our laboratory has a documented quality assurance system in place to ensure the proper functioning of all equipment and reagents. All new reagents are thoroughly tested before entering the production line. We also purify a control sample along side a batch of real samples to ensure that there is no reagent failure or laboratory-caused contamination. About 33% of all the sample wells in a PCR reaction are controls, ensuring that all reagents are working properly. For each portion of a sample that is tested, the Pink or Blue DNA Gender Test laboratory procedure is run in triplicate. So, for a standard sample, where 2 portions are tested, there are actually 6 data points showing boy or girl, 10 data points with unique controls for that specific sample, and dozens of controls indicating that all reagents were working properly.
The lab documents all this activity and is working towards ISO and CLIA accreditation. Although accreditations are not currently needed for gender testing due to it is not used for medical or diagnostic purposes, the company recognizes that accreditation will add more creditability, and as more regulatory guidelines are expected in the future, it makes good business sense to have a strong, accredited quality system in place.
Hsien: What factors can contribute to inaccurate results? How can consumers ensure the most accurate results possible?
Terry: It is very important that our instructions are carefully followed. The DNA preservation cards must be completely filled with the appropriate amount of blood in all three specimen blotting areas of the card. The quantity of a baby’s DNA in the mother’s blood is very minute. Therefore, the more blood, the more fetal DNA; and the higher the chances are for a conclusive result. It is also important to collect the sample no earlier than 7 weeks, post-conception. Specimens collected earlier than this eligibility date may not have enough fetal DNA circulating in the blood for our DNA test to detect. Contamination of the sample with male DNA from outside the womb can also occur. We have a proprietary method that detects this kind of external contamination, but once contamination is confirmed we cannot provide accurate results and a new specimen is needs to be sent in. The best way to ensure the most accurate results is to follow our instructions, watch our instructional video, keep away from males while providing the sample, collect the proper amount of blood, and make sure that the area used for specimen collection is clean.
Hsien: Why do you think people are so eager to know the sex of their baby before delivery?
Terry: That is a complicated question and one that is highly specific to each individual. We do not survey our clientsâ€™ intentions, but many volunteer their reasons for DNA testing. Most commonly these are to make an announcement at a family gathering, surprise their husband with the anticipated gender, preparing siblings for a new baby boy or girl, and many women are simply excited and anxious about their pregnancy and want to know their babyâ€™s gender as early as possible. They just canâ€™t wait to find out.
Hsien: How would you respond to critics of early gender detection who say that the various methods, including DNA tests and ultrasound, are being used for sex selection?
Terry: There are several companies providing products to select gender, and gender selection is legal in the United States. Check out places like Amazon.com, where gender selection kits are for sale.
However, this is not what we are all about, here. We are about helping people who are excited and want to make an announcement at a family gathering, or surprise their husband with the anticipated gender, or preparing siblings for a new baby boy or girl, or just to help a mother-to-be who is thrilled about her pregnancy and wants to know her babyâ€™s gender as soon as she can.
Our DNA test are not be used for gender selection and our consent for states this. People using our gender testing service have consented not to use it for gender selection purposes. We are clear about this, and we will continue to refuse to provide our services for those means. To further assure this position we regularly turn people away trying to purchase from China and India, where gender selection procedures are of great demand.
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