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Tourettes Genetic Disorder Report

Genetic Disorder Report (Tourette Syndrome)
​Evan Zhou
Tourette syndrome (TS) is a genetic disorder that affects the human nervous system
(particularly the part of the brain responsible for movement called the basal ganglia). It is an
inherited disorder that has a 50% probability of passing down to the offspring. While some
information is still limited, most studies done on tourette syndrome suggest that it is a
dominant autosomal disorder. In 2010, the prevalence of tourette syndrome in Canada was
about 1%. “122,884 Canadians participated in the 2010 and 2011 surveys, with 122 participants
diagnosed with TS” (Jaeun Yang, 2016). Tourettes is also found to be 4 times more common in
males than females. While tourette syndrome is not linked to a shorter life expectancy or any
learning disability, the disorder causes involuntary physical movements or sounds to happen
(tics). There is no cure for tourettes, however current medication for tourette syndrome can
keep symptoms more controlled, thus improving the quality of life.
Rise of Abnormality
Tourette syndrome is a complicated disorder that affects the nervous system of a
human. The exact cause for tourette syndrome is still unknown, but some studies say that it is
an autosomal disorder meaning that it affects one of the 22 autosomes pairs in a human. In a
small handful of cases, mutation of the SLITRK1 gene (gene used to create proteins for brain
and nerve cell development) has been discovered. The causes for tourettes are unable to be
pinpointed but some scientists also believe that tourettes can also result from environmental
factors and not a change or mutation of a gene.
Image of Labelled Human Karyotype
Image of SLITRK1 gene
Although there is no test to diagnose someone with tourettes, there is a criteria that
doctors follow. To be diagnosed with tourettes, both motor tics (movements) and vocal tics
(verbal) must be present, tics have to occur several times everyday, and tics are not caused by
medications or other medical conditions. Usually, symptoms arise in children around ages 6-8
​Graph of Other Conditions Often Linked to Tourettes
with the latest being around 18. However,
there are some other conditions like ADHD
that can cause tics. In these cases, a doctor
might recommend a blood test or an MRI
to eliminate the possibility of another
condition. Someone with tourettes can also
be diagnosed with ADHD/ADD, behavioural
problems, anxiety, depression, or learning
disabilities. Although MRI’s can show the
difference between someone with and
someone without tourettes, No laboratory
tests and brain scans have been developed
to diagnose tourette syndrome.
Inheritance Patterns
Many studies on the inheritance of tourette syndrome have suggested that there is a
probability of about 50% to pass down the gene to an offspring. Some scientists believed that
tourette syndrome was caused by one gene while others believed it was a combination of
multiple. While an offspring can have the gene, they may not show symptoms of tourettes.
Tourette syndrome is also known to affect more boys than girls. When shown signs of
tourettes, commonly asked questions from the doctor include
family health history.
Treatments & Medication
Even after many decades of studying tourettes, there is still no
treatment for it. However, there are a few medications that can
reduce the intensity of tics. Medications that block or lessen
dopamine can be given to patients with tourette syndrome.
“Fluphenazine, haloperidol (Haldol), risperidone (Risperdal) and
pimozide (Orap) can help control tics”. These medications can also
lead to weight gain and involuntary repetitive movements.
Tetrabenazine may also be recommended by a doctor, although it
can cause severe depression. In some cases, an injection of
botulinum into a muscle can be used to relieve a muscle of a motor tic. Tourettes can
often be linked to depression or anxiety because of public judgements or use of
medication with the side effects of depression. Psychotherapy can be offered for people
in these circumstances. A newly developed therapy called deep brain stimulation (DBS)
is also being developed to help with severe tics that can’t be stopped with other
medication and therapy. DBS involves the implantation of a battery-operated medical
device that sends stimulations to areas of the body involving movement. Sometimes,
the frequency of tics can also depend on someone’s surroundings. Tics are believed to
occur more frequently during stressful situations and when one is fatigued or ill.
Developing Treatments
To this day, tourettes is still highly researched as knowledge of the causes, inheritance
patterns, and treatments are still limited. DBS (deep brain stimulation) is a new (still being
developed) therapeutic method used to treat severe tics. With the research of DBS, there is
also a rise in discussion about the ethical issues. DBS requires an implant of a battery device
used to deliver stimulation signals to body parts of movement. Thus, discussion about the risks
of implantation of a man-made device are highly considered. Another technique being
developed is the medical use of marijuana. TAA (Tourettes Associations of America) is a charity
funding the development of new treatments like medical marijuana. Research on use of
medical marijuana is being done in order to find new medications without significant side
effects. Marijuana is classified as a depressant drug because it slows down signals from the
brain. Therefore, marijuana could possibly decrease the frequency of tics. While some medical
marijuana is already being used for some patients in Canada, some patients reported that there
was no effect at all. The use of medical marijuana is a very controversial topic. Marijuana use is
illegal in many places in the world because of the high recreational use. marijuana is also a
depressant drug, so there are some risks with the usage. Thus, debates about ethical issues
usually happen.
While tourette syndrome is a complicated disorder with little known information,
progression on new medication and treatments are being developed every year.
Stimulating research gives new treatment hope for Tourette Syndrome. (2020, June 04).
Retrieved from ​https://www.sciencedaily.com/releases/2020/06/200604152106.htm
Risk Factors and Causes for Tourette Syndrome. (2020, May 13). Retrieved from
Tourette syndrome. (n.d.). Retrieved from
Tourette syndrome: MedlinePlus Genetics. (2020, August 18). Retrieved from
Yang, J., Hirsch, L., Martino, D., Jette, N., & Pringsheim, T. (2016, April 05). The Prevalence of
Tourette Syndrome in Canada: A National Population-Based Study (P1.047). Retrieved from
Mandal, D. A. (2019, February 27). Tourette Syndrome Prognosis. Retrieved from
Tourette syndrome. (2018, August 08). Retrieved from
Tourette's Disorder: Tic Triggers. (n.d.). Retrieved from
Glickman, A., & Sisti, D. (2020, April 01). Prescribing medical cannabis: Ethical considerations for
primary care providers. Retrieved from ​https://jme.bmj.com/content/46/4/227