As we took the lights off of our tree in the Diagnostic Lab at GGC this year, we started thinking… ‘What do our genes and holiday lights have in common?’
That’s probably not a question you had ever considered. But, I’ll give you a hint – it has to do with expression.
Even if all the bulbs on every strand of lights are working and connected just right, a Christmas tree cannot express itself or ‘do its job,’ until the switch is flipped and the lights are turned on. Like a perfectly good strand of holiday lights, even our normal genes need to be turned on to do their job.
Remember in biology class when you learned that all genes have a DNA sequence? For example, a section of DNA may read AAGCTTGCTGTG…. For many genetic conditions, the cause of the symptoms is a typo in that sequence, for example there’s an A where there should be a C. But what if a patient has a gene that is sequenced correctly, but it is simply not turned on? Well, just like a tree that is not plugged in, that gene isn’t expressed. It can’t do its job – which can cause all sorts of problems.
There are many factors that affect gene expression, or when and how genes are turned on and off. This area of study is called epigenetics. Methylation is one way that gene expression is controlled. All of our genes may be sequenced correctly, but when a specific chemical tag, called a methyl group, attaches itself to a gene, it turns it off and prevents it from functioning. This process is often normal. For example, you have genes for eye color present in every cell of your body. However, in the cells of your heart, those eye color proteins are not needed so they are simply switched off.
In other cases, the gene should be expressed, but because of faulty methylation, it isn’t. The gene itself is fine, but it’s not being expressed. In those patients, faulty gene expression can make it look like there is a genetic sequence typo. Patients with clear features of a genetic disorder may find that their sequencing testing is normal. The gene sequence is fine, but it’s simply not being expressed.
So how can you tell if a gene is being expressed like it should?
In 2019, Greenwood Diagnostic Labs at GGC partnered with London Health Science Centre (LHSC) in Ontario to launch a new type of genetic test called EpiSign. EpiSign looks at these chemical tags (methylation) and identifies ‘epigenetic signatures’ that are unique to certain genetic conditions. EpiSign started with the ability to identify 19 conditions, and as we have learned more about epigenetics and identified new signatures for more conditions, it has expanded each year. GGC has completed over 1,000 EpiSign tests, and the most recent version, EpiSign v4, is being launched this week and now includes testing for over 70 genetic conditions – providing patients with answers that were not detectable by traditional methods of genetic testing.
Dr. Bekim Sadikovich of LHSC initially developed the testing process and ability to interpret these epigenetic signatures. In 2016, Dr. Sadikovich partnered with Dr. Charles Schwartz, who was the Director of Research at GGC at that time, to introduce this new technology to GGC. From those early partnerships, Greenwood Diagnostic Labs at GGC along with LHSC and Amsterdam University Medical Centers launched EpiSign in 2019. Greenwood Diagnostic Labs became the first lab in the United States to offer EpiSign to patients, and remains the only US lab providing this testing. In recent years, EpiSign has garnered attention through numerous publications and success stories, and has expanded to labs in the United Kingdom and Australia.
Over the past four years, EpiSign has provided an answer to many families whose diagnosis had been missed by traditional genetic testing technology. Parents have been able to breathe a sigh of relief when their child’s diagnostic odyssey has ended after a journey that, for many, has lasted for years. Clinicians can now give their patients a quick and accurate diagnosis. The question now changes from “What does this patient have?’ to “How are we going to treat them?”
So, when the holiday season rolls around again, pay attention to those lights and remember that when you see Christmas trees ‘doing their job’ this holiday season, think about gene expression and the novel work that is taking place at the Greenwood Genetic Center.
Post by Caroline Pinson, Marketing Specialist for GGC’s Greenwood Diagnostic Labs