January 22, 2009

DTC genetic tests II

Direct-to-consumer (DTC) genetic tests: is this the medicine of the future? (Part II)

I wrote that DTC
genetic testing is a type of genetic test that is accessible directly to the consumer without having to go through a health care professional. The development of genetic tests marketed and sold direct-to-consumers (DTC) via the internet raises moral concerns and debate about their appropriateness and ethical and clinical significance. These tests are offered for a wide range of diseases and conditions, and the mutations have variability in penetrance and associated risk. A number of these tests lack data on their accuracy and reliability, making interpretation of results difficult. DTC genetic testing is undertaken outside the context of the physician-patient relationship and may lack appropriate individual and family genetic counseling, leaving the consumer vulnerable to potential harms, such as misinterpretation of results, including false positive or false reassurance, with limited or no benefits. I tried to organize the DTC test in 5 main groups:

1. Genetic risk disease test
2. Personal Genome decoded
3. Ancestry assessment
4. Home paternity testing
5. Miscellaneous

In a prior post (DTC genetic tests, Part I) I talked about some of the companies that offers products in the two first groups. Let’s continue with this theme analyzing the remains groups.

Ancestry assessment

One important group is the companies that offer Ancestry DNA tests and genealogical studies. Well, they don’t really give the test only kits to get the samples. The testing process offered by these companies often includes taking a cheek swab and returning the testing kit to the company. This is a good practice. Limitations: the information that they use in their analysis is still incomplete due to an insufficient data in their own databases and there is no clear connection between DNA and racial/ethnic identity. But it’s still a very interesting idea. The ancestry results included in their complete scan are a genetic atlas, an assessment of ancestral origins, the male lineage Y-Chromosome groups and the female lineage with mito-groups of Mitochondrial DNA. At least two dozen companies market genetic ancestry tests, which typically cost between $100 and $900, according to the scientists. As public interest has grown, nearly half a million people have had their DNA analyzed for ancestral studies.

Some examples of these companies are DNA Ancestry that
promote discover genetic genealogy and ancient ancestry with a DNA cheek-swab test, find leads based on DNA testing, surnames, geography and haplogroups, expand the consumer family tree, find potential genetic cousins, see maps and make connections, teach about the science, lab work and value of your genes in tracing your personal family history, they explain and help you choose a mitochondrial (mtDNA) or Y-chromosome lineage test in a few easy steps; and The Sorenson Molecular Genealogy Foundation is a non-profit organization dedicated to building the world's foremost collection of DNA and corresponding genealogical information. They invite to consumer to add their DNA sample and four-generation genealogy to the 90,000 records in the Sorenson Database to build the genetic family tree.

Now we need to discuss widely the real limitations of Ancestry tests even if I like these stuffs!

Home Paternity Tests

In my experience the DTC tests in paternity or related studies is a lethal weapon for a wide group of consumers. The reasons to choose this kind of test are many. Sometimes to confirm a suspect situation, sometimes to close a familiar problem but generally the parents do this test with no knowledge of the other side and mainly the children are the affected. There is no excuse. Bioethical implications involve mainly the Informed Consent of the actors and in a second view all the four principles from bioethics -non-maleficence, beneficence, respect for autonomy and justice- that I cited previously.
The American College of Medical Geneticists recommends that any genetic testing should be provided to the public only through an "appropriately qualified health care professional", who will order and interpret the test. The Human Genetics Commission in the United Kingdom recommends that genetic testing be accessed primarily through health care services and professionals. The context emphasized is one where a health care professional, physician, or genetic counselor provides guidance to a particular patient about what is, or is not, in his/her best interests.

The motivation for these recommendations is to protect patients, ensure a patient is properly informed about a genetic test and its significance (or lack of), and provide appropriate information and guidance to the patient about actions to take or avoid in light of results. Both professional bodies highlighted the complex and sensitive nature of genetic information, the potential difficulties in understanding and interpreting the results, the potential harms associated with this information, and the need for caution and guidance of health care professionals.

There are two ways to conduct paternity testing. They are both 99.99% accurate. The difference is in whether the testing process is legally documented, so that results can be used in court for legal purposes. Home paternity testing or self-collection testing, is a simple and easy way to determine a father-child relationship in the privacy of consumer own home. They use a simple cheek swab kit to collect your own DNA samples from the child, father-in-question, and mother. Then, it mail the samples to the lab at your convenience. Your results are delivered online, in a password -protected account or by post.

Home paternity tests use the same laboratory process as legal paternity tests, but the results are for personal use only. Legal paternity testing, also called chain-of-custody testing, is required if the customer need to prove paternity for legal reasons — such as child support, custody or immigration. For this testing, a company representative collects the DNA samples from you and legally documents each step of the paternity testing process.


Of all the TC 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. The Pink or Blue Gender Test from Consumer Genetics 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 complexity, they regularly run at least 2 tests for each sample to increase the probability of a conclusive result. If all tests are inconclusive then they ask the customer for a new sample.

Others interesting test are the products for the lifestyle category include like CaffeineGEN™ and WineGEN™, from Consumer Genetics too. These Lifestyle products assist to consumer in making proactive choices to self-managing their well-being by addressing how daily health-related decisions can affect the life based on your personal genetic make-up.

This is the apperitive of the big menu that will come soon, enjoy it!

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