Tourette syndrome is characterized by repetitive
movements and the production of unwanted sound
- Tourette syndrome
has for long been known to have a genetic basis
- Copy number
variations in NRXN1 and CNTN6 were found to be significantly associated
with Tourette syndrome
- These variations
were found to increase the likelihood of developing Tourette syndrome
The condition has no cure till date, but the symptoms can be managed with treatment.
Individuals with this disorder were offered hope recently, when a research team
that carried out a large study on Tourette syndrome identified genetic
abnormalities, which are the first genes that are shown to have significant
association with the condition.
condition has always been believed to have a genetic basis, but no specific
gene was identified as having a significant association, until scientists from
Purdue University utilized a gene sequencing technique that focused on a larger
area of the genome. One of the main scientists associated with the study, Dr.
Peristera Paschou, said that this approach was more efficient than focusing on
a single gene.
‘The newly identified genes can be used as genetic markers for early identification of the condition.’
Copy Number Variation
Paschou further stated that focusing on a single base pair mutation, which was
the main building block of the genome, has now given way to broader approaches.
The scientists examined the number of times a specific sequence of genes was
repeated in the genome; these sequence variations are called copy number variations.
The number of repetition of these sequences can have a direct effect on the
health of an individual.
sequences of DNA that are repeated could involve
- Large sections of
the DNA sequence
- Complete genes
scientific community has only recently begun to understand the significance of
copy number variations and the onset of disease.
research team from Purdue University scanned through the entire genome to
identify the sequence that varied in numbers among patients with Tourette
syndrome. This involved a lot of physical analysis and the entire genome had to
Significance of the Study
number of copy numbers and the association with the disease was highly
significant, which is a considerable breakthrough in the research on Tourette
significance of this finding has been highlighted by Dr. Jeremiah Scharf, who
is the co-senior author of the study and a professor at Massachusetts General
Hospital's Department of the Psychiatric & Neurodevelopmental Genetics
Unit. The professor stated that their study was aimed at establishing that
- Tourette syndrome
was not a simple single gene disorder
- There was a
statistically stringent number of genes that were required to develop this
two genes that were identified had a statistical significance associated with
the disease, the results of the study were published in the journal Neuron
. 57 researchers were involved in
the study that spanned 11 countries.
is a complex
neurological disorder which is characterized by repetition of words or sounds
by the affected individual. In a very small percentage of the people, it can
lead to the repetition of obscene words.
signs and symptoms include:
- Clearing of the
- Blinking of the
phonic or tics
symptoms are mild but they develop as the child grows. Some patients are also
found to be associated with
condition is first identified between the ages 7 to 10, after which it takes a
turn for severe. Sometimes the condition is characterized by sudden rage and
anti-social behavior. The treatment for this condition is behavior therapy and
there is no known cure.
The Genes under Study
individuals with Tourette syndrome were included in the study with 4000
individuals analyzed in the control group.
results of the study showed that Tourette syndrome was associated with
- Deletions in the
- Duplications in
the CNTN6 gene
- In the study, one
of the genetic variants was present in nearly 1 in 100 people with
genes NRXN1 and CNTN6
during brain development and with the production of molecules that are
associated with the connections between the cells. They are also associated
with the cortico-striatal-thalamo-cortical circuit, which involves the loop of
brain cells that connect the brain cortex with the regions of the brain which
are involved in processing movement and emotions. Abnormalities in this circuit
can lead to Tourette syndrome.
two genes have been associated with other neurological disorders but this is
the first study that has found that copy number variations in these genes could
lead to Tourette syndrome.
current study provides an insight into the biology of the disease and further
studies will reveal a better understanding of how this region of the brain
develops. The study involved thousands of participants but the scientists
associated with the study are planning on conducting an even larger study. This
would provide further insoghts into the cause for the condition.
- Researchers uncover genetic gains and losses in Tourette syndrome - (https://www.nih.gov/news-events/news-releases/researchers-uncover-genetic-gains-losses-tourette-syndrome)
- What is Tourette Syndrome? - (http://www.tourette.org.au/about-tsaa/what-is-tourette-syndrome/)