The Sequence 8/14-8/20
Genetic Testing in Thyroid Cancer, Preimplantation Genetic Testing with Few Embryos, A New Way to Identify Cerebral Palsy with a Genetic Etiology, Genetically Modified Animals as a Trade Secrets
Genetic testing of thyroid cancer tumors can help decide on the right treatment for patients
Rui Wang et al. found that different genetic mutations in Anaplastic Thyroid Carcinoma (ATC) tumors (Anaplastic Thyroid Carcinoma is a type of thyroid cancer) correlate to different survival outcomes among patients.
So, what does cancer have to do with genetics anyway?
Cancer develops when mutations, or harmful changes in the DNA, occur in the genes that regulate cell division (FYI your cells are dividing and replicating ALL the time). This causes uncontrolled cell division. So, a tumor is essentially a group of cells that grew uncontrollably due to genetic mutations in the DNA.
It’s possible to do genetic testing on cancer tumors in order to see what genetic mutations it has. In fact, we’ve been doing it for a while. It’s been fairly common practice to perform genetic testing on breast cancer tumors to see what treatment option may be best based on the genetic mutations in the breast cancer tumors.
How does genetic testing of ATC tumors make a difference in patient outcomes?
Well, the team found that patient survival rates increased when tumors were comprised of BRAFV600E mutations, and significantly decreased when tumors were comprised of RAS mutations (BRAFV600E and RAS are genes). It’s also important to note here that patients with BRAFV600E mutations may receive BRAFV600E-directed therapy, increasing survival outcomes.
The takeaway? Genetic testing and mutation analysis should be considered in all patients with ATC. Cool, huh?
Now, although ATC is a very rare cancer, this is important overall because the more that treatments can be targeted based on the type of genetic mutations identified in tumors, the more patients can be successfully treated. And THAT, my friends, is precision medicine.
Is preimplantation genetic testing in embryos useful in women with few embryos available?
Preimplantation genetic testing (PGT) is the process of testing embryos after in-vitro fertilization (IVF) prior to fertilization in the womb in order to test for genetic mutations. This is usually done when couples are at high-risk of having a child with a genetic condition based on their genetic carrier status. This can include testing the embryo for a single, specific gene mutation that mom or dad carries, or for an entire extra or missing chromosome (aka aneuploidy). By doing this, only the embryos without a genetic mutation or variation are transferred for fertilization.
Whether to do PGT can be a tough decision for women who only have a few embryos to transfer, because there is a risk of harming the embryo. To try and understand the utility of PGT-A (PGT for aneuploidies) in cases where embryos are limited, Mahesan et al. studied 130 patients with low embryo count who underwent PGT-A on all embryos, as well as 130 controls who did not undergo PGT-A.
Was PGT-A worth it?
In short, no. The group found there was a significant increase in live birth rate per oocyte retrieval in women in the control group compared to women undergoing PGT-A, and no difference in the spontaneous abortion rate (you would expect spontaneous abortion to happen if the embryo did in fact have an aneuploidy).
A new way to clinically identify cerebral palsy with a genetic etiology
Cerebral palsy (CP) describes a group of permanent disorders of movement causing activity limitation that are attributed to non-progressive disturbances in the developing fetal or infant brain. It is a diagnosis that is made clinically, most reliably after two years of age. In recent years, it has been shown that genetic testing in the cerebral palsy population identified a genetic etiology for CP in ~15% of cases. One of the most common genetic etiologies for CP is Hereditary Spastic Paraplegia (HSP), a group of neurodegenerative disorders presenting with spasticity, usually starting in the lower extremities. As the clinical picture of CP and HSP can look very similar, especially in children and young adults, the only way to identify the diagnosis of HSP in patients with CP is through genetic testing.
So how can we diagnose hereditary spastic paraplegia clinically?
MacWilliams et al. combined multiple gait (the way in which someone walks) and physical exam measures to differentiate between these two diagnoses. They did this by doing a retrospective study of medical records containing these exam measures in patients with CP and patients with HSP, feeding it to a statistical analysis, and voila! We have a tool that can predict diagnostic probability of HSP. This is the first time providers may be able to differentiate between CP with an environmental etiology and HSP without genetic testing, or, identify a good reason to order genetic testing on patients with a high diagnostic probability of HSP.
Court considers genetically modified animal a ‘trade secret’
For years, different foods have been genetically modified to do things such as increase production and shelf life, and resist diseases and pests. This week, a court case reached a new level as one company is being requested to pay $10 million for illegally attempting to sell genetically modified shrimp that was improperly acquired from another company.
Interesting. Why does this matter?
The company is being required to pay out because the genetically modified shrimp they attempted to sell are being considered ‘trade secrets’, since they were specially bred to be resilient. This is the first time that the manner in which a living organism was successfully bred has been considered a ‘trade secret’ in the court of law. This is important because this begs the question of whether the way that ANY living being bred could be considered a trade secret. Consider horses, for example. Horse breeders have their own special ways of raising horses to ensure the welfare of breeding horses, for example by using surrogates when a mare cannot carry her own foal, and to preserve bloodlines to maintain a wide genetic pool to support the recovery of rare breeds. Will these methods be considered ‘trade secrets’ in the court of law in the future?
Want to receive The Sequence every week? Subscribe below!