Is Schizophrenia Entirely Genetic?

Could Schizophrenia Be Entirely Genetic?
By MedHeadlines • Mar 29th, 2008

The latest gene-scanning technology may have shed some much-desired light on a potential cause for schizophrenia, a mental disorder characterized by delusions and scrambled thought processes. The disease is believed to affect 1% of the population.

Until now, medical scientists were searching for the cause of the disease in a cluster of factors, none of which produced particularly promising results. Previous studies have searched for shared genetic sequences among patients and how the drugs prescribed for the disease work with brain cells. The cause has remained elusive but recently developed high-resolution technology capable of scanning the complete DNA map has revealed some very rare genetic variations common in schizophrenics that have been heretofore undetectable.

The discovery, considered a paradigm shift by colleagues, is the result of a combined study involving researchers at the National Institute of Health, Cold Spring Harbor Laboratory, and the University of Washington in Seattle. Researchers scanned blood samples from 150 schizophrenics and a control group of 268 samples from people who do not have the disease.

53 mutations in the DNA sequence were detected. These mutations were found to occur in 15% of people with schizophrenia and 5% in those not affected by the disease. The disease usually becomes apparent in adulthood but a very rare form sometimes develops during childhood. When the blood samples of people with this rare childhood form of the disease were analyzed, a rare mutation known to alter genetic function was four times more likely to occur. Heredity plays a role in some of the mutations identified but others spontaneously occur at or shortly after conception.

One of the ways the genetic mutations affect brain function is by distorting the ability to guide neurons to the correct locations in the brain during development. Another alters the shape of a glutamate-transporting molecule. Glutamate is required to excite neurons so signals can be effectively transmitted from cell to cell.

Researchers haven’t yet determined if these genetic mutations work alone to cause schizophrenia or if they work in conjunction with other processes. The research team is optimistic, however, that the ever-improving state of gene-scanning technologies will help solve the mystery of this very disturbing disease.

They also express the hope of using similar technologies to learn more about other diseases of the mind, including autism, bipolar disorder, and depression.

Today’s issue of the journal Science carries complete details of the study.

I am fortunate to not have schizophrenia; but I can't say I agree that it is entirely genetic. I know people who have parents, siblings or other family members with this disorder. There always seems to have been an outside trigger.

If it were entirely genetic wouldn'it always pass from parent to child? Is it like twins, which skip a generation?

Comments

No, many things that are entirely genetic aren't always passed directly from parent to child. Eye color, for example, involves multiple genes which can be dominant or recessive from both parents. Simply put, my brown eyed kid could have brown eyed kids but blue eyed grandchildren. Wikipedia has a concise article on basic genetics that explains all that a bit more.

With that said, studies have been done on identical twins with schizophrenia. In some cases one has schizophrenia and one doesn't. There's been a fair amount of research done in that area if you want to read up on it. It doesn't mean schizophrenia isn't genetic, just for some reason those genes may not have been turned on in one of the twins. That "turning on" could be events or something in the genome we don't quite understand yet.

It's really interesting, and something I haven't read up on since college. I should crack open some books.
 
Just my input to your comment: If it is entirely genetic, it might pass from parent to child. We inherit half of our genetic material from one parent, the other half from the other. In turn, we only pass on a random half of our own genetic material.

Sometimes the specific gene - or genetic mutation - need only to be passed down from one parent to occur in the child (dominant), sometimes both parents have to pass down the same gene/mutation for it to show up in the child (recessive). In recessive cases, the trait can be passed on for generations before it shows up. If there is a dominant inheritance pattern, the child can only pass the disease or trait on if he/she himself has it.

Well, so far so good. Sometimes we just inherit a predisposition to a disease. Then some trigger mechanism, mutation, or chemical is needed for the disease to manifest in that particular individual. Here, you talk about mutations that appear to be passed down combined with apparently random mutations... starting to get complicated... Looks to me that further research is needed to be able to explain this fully.

I guess there are others here, though, that can explain this better than me! I'm struggling a bit with my English over this one...
 
In most cases, if you have a first-degree blood relative (e.g. parent/grandparent, sibling, cousin, uncle/aunt, etc.) with mental illness, then you have a statistically greater chance of also being diagnosed with a mental illness. Countless studies have looked at every DSM diagnosis from chemical dependency, mood disorders, personality disorders and dissociative (e.g. psychosis, schizophrenia) and the relationship between relatives and a strong concordance rate is found.

I do not practice psychiatry, but I have always theorized that there may be a genetic predisposition to disease as mentioned above with a triggering mechanism to rise to the level of actual diagnosis. God knows how many truly psychotic or schizophrenic patients there are out there, but so many cases are diagnosed every year that I wonder if pre-screening of those at risk might not be a bad idea.
 
Referring to Snoozan's response: Don't identical twins have the exact same genes? If I understand genetics correctly, they do, and if so, the fact that in some cases of identical twins, one has schizophrenia and the other doesn't, would suggest that schizophrenia is NOT genetic.

I don't claim to have all the answers on this though, and I have a limited understanding (since the extent of my biology studies are one year in high school and one year in college).
 
No, many things that are entirely genetic aren't always passed directly from parent to child. Eye color, for example, involves multiple genes which can be dominant or recessive from both parents. Simply put, my brown eyed kid could have brown eyed kids but blue eyed grandchildren.
That's true I guess I should refresh my memory on Punnet Squares. :tongue:

With that said, studies have been done on identical twins with schizophrenia. In some cases one has schizophrenia and one doesn't. There's been a fair amount of research done in that area if you want to read up on it. It doesn't mean schizophrenia isn't genetic, just for some reason those genes may not have been turned on in one of the twins. That "turning on" could be events or something in the genome we don't quite understand yet.
Sounds like I need to visit the library! It's that "turning on" or "trigger" that I find most interesting.


Posted by snoozan
=====================================


I do not practice psychiatry, but I have always theorized that there may be a genetic predisposition to disease as mentioned above with a triggering mechanism to rise to the level of actual diagnosis. God knows how many truly psychotic or schizophrenic patients there are out there, but so many cases are diagnosed every year that I wonder if pre-screening of those at risk might not be a bad idea.

Posted by samhung
=====================================
I think it might be a bad idea. There have been women who were tested and told that in 20 years they might get breast cancer; and they opted to have prophylactic radical mastectomies! :eek:

Since there is no cure for schizophrenia where does that leave people who may carry the gene? Will that lead them into a crippling depression or ignite something in them to be more successful sooner. Live life to the fullest as it were.


Referring to Snoozan's response:
Don't identical twins have the exact same genes? If I understand genetics correctly, they do, and if so, the fact that in some cases of identical twins, one has schizophrenia and the other doesn't, would suggest that schizophrenia is NOT genetic.
Oooo, good point.

I don't claim to have all the answers on this though, and I have a limited understanding (since the extent of my biology studies are one year in high school and one year in college). Same here :tongue:


Posted by whatireallywant
 
In my short, albeit extensive experience with psychology (undergrad, grad, and practice with a forensic population), Twin Studies in Psychology are successes in science for the fact/s that they prove environment plays an exremely significant role in psychopathology. A) Schizophrenia is highly genetic. B) Twin Studies show, that while both twins may have the gene code for schizophrenia, one raised in harmonious and well-to-do families may never ever show signs or experience symptomology. However, the fact that the other can, i.e has experienced a different, less healthy/trigger-inducing environment, shows that the nurture aspect is just as influential in genetics as the nature aspect, though not more...considering issues in biopsychology anyway.
 

Blog entry information

Author
Principessa
Read time
2 min read
Views
238
Comments
6
Last update

More entries in General

More entries from Principessa

Share this entry