Genetics has always been a fascinating subject to me, as a marine biology major I was pleased when I
saw that it was one of my required classes to take. While I have learned so much in the semester I took this class
there is just much more I wanted to dive in within the world of genetics. The topic I choose for writing this
paper was genetics role in mental illnesses, as I realized this was too broad of a subject I narrowed it down to
the role genetics may play in major depression.
The question of whether or not depression can be genetic and what causes it is a very broad question
with a significant amount of possible answers. While depression can be brought on for a number of reasons
whether or not depression can be genetic and the evidence that it can run in families is sparce and few between.
Unlike some diseases that have a known mutation of a gene that causes disease depression is different. Research
has been done to find the answer on if depression can be brought on genetically or not. If someone is diagnosed
with depression at a younger age it is more likely to be hereditary.
Approximately 9.5% of American adults 18 years or older end up suffering from some type of
depressive illness whether it be major depression or bipolar disorder. Depression is a complex disease that no
one is entirely sure what causes it, it can be caused by ones environment, medicine changes, or even genetically.
A family history of depression can potentially lead to a higher risk of developing depression. One of the biggest
questions asked about depression is if there is any genetic connection to depression or if there is a “depression
gene.” While researching around the genetic connection to depression I stumbled upon a study that showed
British researchers isolating a gene that saw to be common in multiple families they studied that suffered from
depression. The research team identified genome wide significant linkage to chromosome 3p25-26 which was
found in over 800 families that suffered from reoccurring depression. It was reported that the heritability of
depression is approximately 40% I also saw that with twins it increases to 70% if the twins suffer from recurrent
depression. So how exactly do we know that genes can possibly play a role in causing depression? In order to
do this researchers will start by looking at possible patterns of mental illness in families in order to determine
their “heritability.” The study I mentioned above proceeded their study by finding a person with a twin that
suffered from depression and finding out if the other suffers from depression as well. Identical twins are good to
look at for multiple scientific studies as they share all of their genes, non-identical twins only share 50% of their
Kelsy Smith
Professor Rinehart-Kim
BIOL294
9 December 2022
I love science
genes. The un-ill twin would likely be at more of a risk to getting depression than the un-identical twins
if genes were to be the cause, and it was found that it seemed to be the case relating to depression. This research
found that in most cases of depression about 50% of the cause could be genetic related and the other half be
unrelated. It even means that for twins the possibility of depression could be entirely related to genetics.
Everything found from the study it found that depression could be completely related to genetics or not at all
and that there was a possibility for both scenario’s there was no solid answer yet. Some non-genetic related
causes were also found from things like history of abuse within a family would also be the cause for depression
as well as several other non-genetic related causes like severe life stress. From all this research there was still no
true “depression gene.” Some diseases however are caused by a defective gene such as muscular dystrophy this
is an uncommon disease. For common diseases however like depression they can also be effected by genes but
a number of different genetic combination changes that could lead to the diagnosis of depression for some
people. Unfortunately scientists do not know how many genes could be directly involved in the cause of
depression but it was unlikely that any one gene stood out to be directly linked to depression in a significant
amount of people.
In conclusion I found people can develop depression overtime from different causes such as
environmental stress factors and many more things and that there is a further genetic cause more research needs
to be done but the existing cause seems likely. From this existing information I think it would be a great benefit
to not disregard the possible link between someone’s depression diagnosis being caused from someone’s
genetic background. Genetics can be used to help to identify problems in people’s lives and can be used to help
get ahead of certain medical needs and identify changes or even mutations in your DNA. Research is still being
done to see if there is possible one gene that can cause depression.
Kelsy Smith
Professor Rinehart-Kim
BIOL294
9 December 2022
I love science
Citations
Breen, G. et al. A Genome-Wide Significant Linkage for Severe Depression on Chromosome 3: The
Depression Network Study. The American Journal of Psychiatry;
https://ajp.psychiatryonline.org/doi/full/10.1176/appi.ajp.2011.10091342 (2011).
Sall, S. et al Analysis of Major Depression Risk Genes Reveals Evolutionary Conservation, Shared Phenotypes,
and Extensive Genetic Interactions. Frontiers in Psychiatry;
https://www.frontiersin.org/articles/10.3389/fpsyt.2021.698029/full (2021).
Davies M. et al. The Genetic Links to Anxiety and Depression (GLAD) Study: Online recruitment into the
largest recontactable study of depression and anxiety. National Library of Medicine;