Craig Venter spend billions in developing new
technologies that allow rapid and accurate sequencing of DNA. This brought
enormous benefits for biological and medical research, and allowed for
better treatments and diagnostic tools.
Genetic testing is one of the fields that greatly benefited
from these outcomes. As we know from famous TV series, today is possible to
finger out a criminal by analyzing a single hair or a tiny drop of saliva. A
more widespread application of this technology is that of paternity testing. A
doubtful father can easily order a DNA testing kit, take a sample of himself and
his child and send it out to a DNA testing facility. In a matter of days, he
will receive a report confirming of ruling out his biological fatherhood on that
child.
Although establishing paternity is the most frequent reason
for having a DNA test done, there are many other applications. For example, it
is also possible to determine other familiar relations such as
brother/sisterhood, maternity, paternity when the alleged father is not
available and so on. People can also have a detailed analysis about their ethnic
and genealogical background. These kinds of tests are often made out of
curiosity, but sometimes they can be very helpful. It is frequent that people
are excluded from certain benefits that are intended for a specific ethnic
group, such as Native Americans because they cannot demonstrate their ancestry.
DNA testing is an effective and conclusive way to prove a person’s ethnic
ancestry.
So far, everything looks fine. You need to have a DNA test
done, so you do some research online. What you will find is an overwhelming
spectrum of DNA labs offering paternity tests, and of course, each of them
claims that they are “the best lab”. What to do? Pick the first you come across?
Pick the cheapest? You don’t need to be an expert to decide, but knowing the
difference among all those labs will allow you to make a wiser decision. Why is
this important? The kinds of questions you seek to answer through a DNA test are
not trivial. A man who is not sure if he is the true father of his children
cannot accept a “maybe” as an answer, can he? Well, that is what he’ll get if he
chooses a cheap DNA test from an inexperienced lab.
All DNA tests are essentially similar in their bare basics:
they are all based on the same biological principles and use the same kind of
analytical methods. There are, however, some differences you should take into
account.
One important difference is the number of genetic markers
they look at. Genetic markers are simply specific regions in the human genome
that tend to be different among people. Imagine there is a region for which
there are 5 different “types” among humans. You are most likely to have the same
type as your father at the same region. However, since there are only 5
different types in the population, your are also sharing the type with many
other people that are not related to you, so that looking at this single region
will not tell for sure who your father is. If we look at another region, the
chances for sharing both of them with unrelated people are lower, but it is
still possible. As the number of markers increase, the probability of a random
match (sharing the same markers with an unrelated person) is lower. The best
paternity tests use as much as 16 different markers. Having a match for all 16
markers by chance is virtually impossible, so a perfect match conclusively tells
that the two persons are father and child. Why not using even more markers?
Because there is no need to (with 16 markers, the probability of a false result
is nil), and adding more markers to the analysis would only make the test more
expensive. Why not less than 16? Many labs use between 4 and 8 markers to make
the test cheaper. By choosing one of these you may save a few dollars, but your
doubts will not be completely wiped out. Do you find this acceptable? Surely
not.
The second most important source of false results of DNA
testing is, paradoxically, one of its strengths. DNA tests are based on a
technique called PCR (for Polymerase Chain Reaction). PCR was a revolutionary
invention that warranted its creator a Nobel Prize. One of the most important
features of PCR is its sensitivity: it is possible to analyzed minute amounts of
DNA (in theory it can be done with a single cell). On one side, one can analyzed
DNA from a single hair, a tiny spot of blood or even from the saliva obtained
from a used cigarette, but the high sensitivity has a downside: it is very easy
that such small samples become contaminated with DNA from other individuals,
such as the police detective that gathered blood spots at the crime scene, the
lab technician who processed the sampled and so on. Truly professional DNA labs
follow strict guidelines and protocols to avoid contamination and have
University-trained personnel. In this regard, if you send your DNA sample to an
inexperienced or ill-equipped DNA lab, you risk a false result since somebody
else’s DNA may be analyzed instead of yours due to improper manipulation or use
of cheap or defective lab materials.
If you are thinking of having a DNA testing done, being for
establishing paternity, genealogical inquiry, determination of Native American
status or other reasons choose carefully. Avoid labs offering very low prices.
Check thoroughly to have an idea about the price ranges out there. Only labs
offering a multi-marker (ideally 16 for the standard paternity test) tests
should be trusted. Avoid labs that, judging from their websites appear to be
small or amateur. Consider that some companies are offering “ready-to-use” DNA
testing labs that can be used by anyone to offer cheap DNA testing. DNA testing
should only be performed by qualified personnel and equipment.
