A blood test has been the go-to examination to deduce the state of a person’s health. These tests can tell us so much about the state of the body, from blood cell counts to levels of cholesterol, enzymes and hormones in our system.
What about DNA tests? Imagine getting your DNA test done just once, and never having to do another test again in your life. Seems like a plausible idea, right? you’ve sequenced your own DNA, and you seem to know everything about your body. Unfortunately that’s quite far from the truth.
A quick comparison
The analysis of the genetic material is indeed very informative, it helps find out a person’s predispositions, characteristics and vulnerabilities. With the help of genetic testing, numerous diseases such as Down syndrome, cystic fibrosis, and achondroplasia can be detected. Gene testing enables the calculation of the probability of developing diseases such as diabetes, gout and Alzheimer’s disease. However, some conditions of the body, whether it be intoxication, infection or organ failure, cannot be determined by genetic testing; These can only be detected with classical methods, and that’s the first drawback.
Moreover, genetic tests are not quick, well at least not with today’s tech, rendering them pointless if a patient is rushed in with an emergency. During an emergency, an attending physician will choose an already developed strategy, and will order standard tests in order to quickly determine the causes of the emergency, and decide a treatment approach.
The different types of genetic tests
Now, just like there are various blood tests, there are also several types of genetic tests each of which achieves specific results.
Using this method, it is possible to estimate the quantity and quality of chromosomes. Normally, a human should have 46 chromosomes or 23 pairs, which differ in size, arm length and constriction position.
In pairs, the chromosomes should be of the same size, with the same lengths of both arms and without fragments separated from them. Just as in the next image below.
Also, with the help of simple manipulations, a laboratory worker can carry out differential staining of chromosomes — a method in which chromosomes are stained with a pattern with stripes, while each pair of chromosomes will have its own individual pattern, which makes it easier to identify.
The FISH method
Known as the Fluorescence in situ hybridization (FISH) method. FISH is based on the formation of bonds between paired nucleotides of DNA and RNA fragments. In the lab, it is possible to synthesize a short DNA fragment (probe) containing the complementary information of the target gene (copy the gene, insert T instead of A, replace G — C and vice versa) and use thermal and chemical treatment to make the probe connect to the target gene.
A luminous label, a fluorochrome, is attached to the probe, and after all the manipulations are completed, the sample is studied using a microscope, if the signal from the fluorochrome is detected, then the gene is present in the sample under study, if there is no glow, a conclusion is made about the absence of the gene.
In the above image, Green colouration corresponds to all helicobacter pylori bacteria, red colouration corresponds to bacteria with a gene mutation providing resistance to antibiotics, blue corresponds to cell nuclei, FISH coloring. This photo is taken from the personal working archive of one of HMND’s scientific advisors.
Using the FISH method, it is possible to detect deletions (losses), duplications (doublings), translocations (pathogenic movements) of genes, or major changes in a gene. Especially relevant is the use of this method in oncology, for example, to identify specific mutations in tumor cells that are responsible for resistance to chemotherapy, which makes it possible to select an effective treatment strategy for each clinical case.
The advantage of this method is the relatively high speed of execution, theoretically, the result can be obtained in just one working day as it is not necessary to decipher the whole genome to obtain highly specialized information about one or more genes.
The main disadvantage of the method, however, is the price, which is caused not only by the production complexity, but also by the cost of probe engineering. The fact is that to create a DNA probe, you need to know not just the sequence of the target gene, but also a unique section of 10–100 nucleotides, which is not repeated anywhere else in the genome. Doing this manually is extremely difficult, and commercial manufacturing companies will never reveal this secret as their profit depends on it.
At HMND, we are trying to create a program for automatically searching for unique sequences. The results so far, for such an automatic search, are unyielding: An average general-purpose computer requires no less than a whole month of continuous work, with no guarantee of a positive search result. We hope that with the development of technology and the selection of the suitable algorithm, the duration of the process will be reduced, at least to a few days.
The Biochemical method
This group of methods includes studies that do not directly affect the study of the genome, but allow the detection of target gene products. One of the most famous examples is the diagnosis of phenylketonuria. Instead of sequencing or FISH for several thousand dollars, you can use a biochemical test of urine or blood for just for a few cents.
This group of methods includes methods for deciphering the patient’s genetic material using various equipment. In most methods for deciphering DNA, it is necessary to copy it, and at the moment of copying, or after, its code is determined by indirect signs. One of the more promising methods relies on passing current through a nanopore via which a DNA strand is pulled. A,T,C and G nucleotides have different sizes, helps detect different signals as the strand passes throught the nanopore. The collected signals are then converted into a DNA sequence.
The main disadvantage of the method is its price, but with the development of technology, the price of deciphering a genome is constantly decreasing. In the near future some companies are aiming towards a goal of $100 per sequenced human genome.
On the bright side, genetic sequencing is quite accurate. Nevertheless, the accuracy of sequencing varies greatly and ranges from 80% to 98%, the results are especially successful when using several different methods for the same biological sample.
The perils of genetic testing today
It is worth noting that very often genetic tests are not regulated in any way, especially if we talk about tests that are not carried out for medical diagnosis.
Today, if you run a quick internet search you can find numerous offers from laboratories to find out what percentage of your genes you got from Neanderthals, in what parts of the world your ancestors lived, or what diet you need to follow. Ironically, there are individual reports of discrepancies in the test results from different labs who were requested to perform a particular genetic test.
Genetic testing has become widespread, and in any area where there is a lot of money and a lack of control, charlatans and unscrupulous companies quickly spread, so carefully study the history of the company in which you are going to take genetic testing. Try to imagine the consequences of your genetic data getting leaked into the hands of malicious parties.
Wrapping it up
So, will DNA tests ever replace blood tests? No. We can safely say that DNA testing will never replace a blood test. The DNA test is not a universal Swiss knife, it is a highly specialised, expensive, but very accurate tool that perfectly complements the arsenal of modern doctors.
Medical organizations and governments are already tapping into the power of medical genetic testing to augment healthcare workflows. The Emirate of Dubai, for example, has been investing heavily in augmenting healthcare with genetic testing, and has recently founded the Dubai Genetics Center, one of the flagship initiatives in the MENA region.
We see that innovation in healthcare can be achieved through augmenting diagnosing workflows with genetic testing and genetic counselling. We also suggest that governments should start investing more in population genetics, and consider unifying storage of genetic data. Aside from facilities and laboratories, advancing in that direction requires software solutions that will facilitate and streamline processes with analysing and handling genetic testing, and the data being yielded.