If you want a few well-known examples: Cystic fibrosis, Muscular Dystrophy, Canavan Disease, and Hemophilia.
There's lots of obvious bad stuff floating around in our genomes. It's not surprising that the roots of mental illness, heart disease, diabetes, and others are hereditary too.
There's a huge difference between conditions that are caused by a single-gene defect vs conditions that sometimes arise when a combination of genes are present/expressed in combination with other (e.g. environmental) factors.
> There's lots of obvious bad stuff floating around in our genomes
Too handwavy. Please be specific :)
“In the genes ------------
One pillar of this future approach is a better understanding of the genetics of mental illness. In the past decade, studies of psychopathological genetics have become large enough to draw robust conclusions.
The studies reveal that no individual gene contributes much to the risk of a psychopathology; instead, hundreds of genes each have a small effect. A 2009 study found that thousands of gene variants were risk factors for schizophrenia. Many were also associated with bipolar disorder, suggesting that some genes contribute to both disorders.
This is not to say that the same genes are involved in all brain disorders: far from it. A team led by geneticist Benjamin Neale at Massachusetts General Hospital in Boston and psychiatrist Aiden Corvin at Trinity College Dublin found in 2018 that neurological disorders such as epilepsy and multiple sclerosis are genetically distinct from psychiatric disorders such as schizophrenia and depression (see ‘Mental map’).”
Even that passage of the article you quote doesn't characterise the genes as "bad stuff"; just known genes that seem to correlate with the (contextually undesirable) conditions manifesting.
Your reply to me misses the point that I was making and argues against a point I wasn't making – which strikingly is the very thing that prompted me to counter your top-level post.
In response to your comment:
> You decried those examples as handwavy
To clarify, I didn't say the examples were handwavy; I pointed out the crucial distinction between disorders specifically attributable to specific gene defects (like Huntington's and cystic fibrosis), vs. conditions that arise through the interaction between positively-selected genes and environmental triggers. It's a category error.
What I referred to as "handwavy" was the sentence "There's lots of obvious bad stuff floating around in our genomes" - specifically the phrase "lots of obvious bad stuff".
I was calling this out as an unexamined assumption, rather than a the simple incontrovertible fact that it was presented as.
> and pointed out that moreover this ground had already been covered in the article and that the article concurred with those examples
But the article doesn't concur with those examples.
The commenter listed illnesses caused by specific-gene defects, and the passage you quoted names several psychiatric conditions that are known to not be caused directly by specific-gene defects. Again, a category error.
> Your reply to me misses the point that I was making and argues against a point I wasn't making – which strikingly is the very thing that prompted me to counter your top-level post.
You seem to have read my top comment as directly critiquing the article itself, rather than the approach that has dominated the field (along with the rest of medicine) for decades. (Fair enough that you read it that way.)
I acknowledged to you that the article conveys that some researchers are rethinking the approach, but I don't see evidence of enough of a rethink.
Most importantly, they're still looking at things mechanistically; studying brain structure, going deeper trying to find particular genetic "causes" (after the many years of looking at genes have yielded little useful insight), and proposing some mysterious "p factor" and asserting: "if it is real, it has a startling implication: there could be a single therapeutic target for psychiatric disorders". That's what I mean by the "mechanistic lens".
The core position I'm arguing against, which is presented in the article and by several commenters, is that mental "illness" is likely caused by "bad" genes or biological processes "going wrong". My position is that we should generally assume that the genes are meant to be there, and focus on what in the person's life is causing the genes or biological systems to express in an undesirable way (which is what the practitioners I've named have been doing for years/decades with great success).
I've expressed my position at length in other comments. At the time of writing, the position I've articulated in detail hasn't been refuted. I'd welcome anyone to do so, so I can learn more about the topic.