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XY can get pregnant?
I was unaware that an X chromosome could mutate into a Y and vice versa over the course of a lifetime. Do we know what causes that?
They are not saying that the X chromosome mutates to Y, but rather saying that XY doesn’t define the sex. For example, some people with XY are born with female genitalia and look female their whole lives. Sometimes they don’t find out they are XY until trying to have kids and are unable to. It isn’t like the X changes to Y over time. That isn’t possible.
So not what the phd claims
I think you may have misread. The PHD isn’t saying that XY becomes XX, they are saying, genetically, a person carrying XY can be a cis woman. Biologically, XY doesn’t determine the sex.
I honestly don’t understand. What does define the sex biologically? The genitalia, then? I always understood positions like William’s like “XY is the biologically male sex by definition, if the human develops female genitalia and feels like a woman they were biologically speaking still intended to be a man.” I don’t understand what else there could be on an elemental level to biologically determine the sex.
There’s no one thing that defines sex, that’s what makes it so complicated. What is often thought of as “biological sex” are two clustered sets of checkboxes (e.g chromosomes, genitalia, secondary sex characteristics, primary sex hormone), but people often have a mixture from both lists. Here’s an interesting nature article on it https://www.nature.com/articles/518288a
Very interesting, thanks!
To preface: this is from a previous bout of hyper focus curiosity (i.e. I am not an expert). But the human genome is significantly more complex than “XX chromosome means biological female”. Other genomic markers can trigger that don’t align with the typical, which can result in male reproductive organs on a person with XX chromosome and vice versa. XX and XY are also not the only options. There are three, four, and even five somal groupings (e.g. XXY, XYY, XXX - note that to my understanding, you can’t have all Y chromosomes even in these outliers). If anyone has further information or any corrections for me, I’d welcome them - I’m going off of memory from a couple of years ago and it’s not directly relevant to me (i.e. I am cis-male with no known chromosomal abnormalities)
Thank you for clarifying
It’s weird how your first thought is “the PhD is wrong” and not “I must have misunderstood something” .
“I must have misunderstood something” .
There was a reason I made that comment
Though I disagree with the conservative genitalia = gender ideology
Point being… the phd is wrong!
Or the thought the phd must have meant something else
But sure the phd is wrong if he meant that; just like those anti-vax doctors and anti-abortion doctors
It’s crazy how you’re still insisting that “the PhD is wrong if he meant that”’ rather than figure out that no, what you think they meant is not what they meant, it is not what they said, you are the one misunderstanding what they said. It has to be the PhD’s fault, certainly not yours.
Straight up
Confidently incorrect is the default with these people. I spend most of my time with family aggressively correcting misinformation about my field and related ones. They will die earlier thinking they know more because of Youtube. Getting them to stop taking bad health advice and mystery joint injections from a fucking chiropractor is the latest battle.
The impression of legitimacy enjoyed by chiropractic is too damn high. I was well into my 20s before I ever heard a single word about it being pseudoscience. Walking around (usually on people’s fucking spines) calling themselves doctors, I absolutely believed it was just some sub-variety of physiotherapy, which I guess is the point. In the whole universe of alternative medicine, I think that has to be the practice which has most effectively disguised itself as conventional medicine. It’s gross.
I guess I should count myself lucky for where I grew up: there’s a big/famous chiropractic school in this city, so this creepy motherfucker was on TV commercials all the time:
Never mind quackery; I thought it was legitimately some sort of cult!
I just don’t get how people don’t have the sense to run from someone who looks like that.
Oh you grew up near Atlanta. I, too, am a Sid Williams commercial survivor.
The quackness of chiropractors depends on where you are, in many places it’s indeed just a type of physiotherapy, or better put you have to be a physio to be a chiropractor. Similarly, in practically all of the world osteopaths are quacks while in the US they’re doing evidence-based medicine with particular philosophical accents.
The way chiropractic plays itself as the cure all for any ailment with regular “adjustments” is the real bullshit, it’s straight up a sales pitch to get people in a recurring schedule for that sweet appointment revenue. Don’t get me wrong, when I’ve thrown my back out the best and most immediate relief I’ve found is to have the guy super twist and crack my back loose just so I can get some mobility to stretch and walk. But the way they sell it as you need several appointments a week to stay “regular” is a crock of shit.
I walked in to a chiropractors’ office once to try and see if they’d take me for an appointment, found a brochure proudly proclaiming that chiropractic treatments can help cure autism and cancer, and turned right the fuck around and walked back out.
If you think you need a chiropractor you actually need a physical therapist and anyone trying to tell you otherwise is lying to you.
One of my mates goes to a chiro. The rest of us detail for him how our problems were helped by physios and they were fixed, and stayed fixed, while he needs to see a chiro every 3 months for just exactly the same problems
He describes himself as an idiot, and I believe him. He still goes to a chiro.
Australia has high respect for chiropractic because the King likes them, and when he was a prince he was pretty influential too. No idea why it would be popular outside the Commonwealth
In Australia they are able to request some x-rays. As in the entire spine, which ends up irradiating radio-sensitive organs like the thyroid and ovaries, often in young people. As a radiographer this shit drives me up the fucking wall, especially given the already frustrating battles over inappropriate imaging requests from real, actual doctors. Want to know a contributing factor to the increase in cancers? The absolutely absurd radiation doses people are sucking up over years of over-imaging.
I was well into my 20s before I ever heard a single word about it being pseudoscience.
every fucking tv show and film referring to them as some sort of curer of back issues probably doesn’t help
And the regs are really bad in the country making all that TV.
They provided me valuable placebo (I think). I still have no idea what my issue really was, but at least it’s gone. Never been back to a chiropractor since though.
I find irony that they disregard expert opinions on the things they are experts for (climate scientists for example) but will accept an entire worldview of opinions based on someone being “smart” like the opinion of a software engineer has on philosophy or politics.
Reject the expert on the subject they’re an expert on because that makes them “elite” and they were trained to think that was bad, but accept an unfounded opinion of someone who may be smart in an unrelated field because the opinion is “different” so it must be “smart”
I think this is the trap all self assigned internet intellectuals fall into. They parrot opinions and vibes from echo chambers that discredit real science or real reporting and call it enlightenment. This in itself is stupid, but then even more stupid people are drawn in and suddenly we have a big club of geniuses
Can someone explain to me how some XX people become cis male?
https://static.scientificamerican.com/sciam/assets/File/Pitch_sketch_final.png?w=2000
This is the best resource I’ve seen to show things relatively simply.
The TL;DR is that a whole “Y” chromosome isn’t exactly responsible for “maleness”, the SRY gene is. It’s normally on the Y chromosome, but mutations can occur placing that gene onto the X chromosome. Inversely, someone could inherit a Y chromosome without that gene, in which case they would develop with female traits.
It’s not considered trans because someone with 46XX plus the SRY gene would develop male genitalia, be identified as male at birth, and likely identify themselves as male. For some types of these conditions, there are plenty of people walking around with no clue that their chromosomes don’t match their gender.
Disclaimer: I’m not a geneticist, so i could have explained something along little off.
Outward, their genitals might look like those of the oposite sex.
You’ve heard of xy people and xx people, but wait till you hear about X people!
Or xxx people, or xxy people, or… dies
I googled it for you.
https://en.wikipedia.org/wiki/XX_male_syndrome
In 90 percent of these individuals, the syndrome is caused by the Y chromosome’s SRY gene, which triggers male reproductive development, being atypically included in the crossing over of genetic information that takes place between the pseudoautosomal regions of the X and Y chromosomes during meiosis in the father.[2][7] When the X with the SRY gene combines with a normal X from the mother during fertilization, the result is an XX genetic male. Less common are SRY-negative individuals, those who are genetically females, which can be caused by a mutation in an autosomal or X chromosomal gene.[2] The masculinization of XX males is variable.
Gene expression is not as straightforward as people think. All sorts of weird shit can happen, and that’s not even including gene mutations.
I can try. The cis part means the person’s naughty bits are aligned with their gender identity. The male is their gender identity. So post-bottom surgery it’s perfectly possible. If you use different definitions for concepts though you will have difficulty making it work.
None of this has anything to do with the claimed PhD in genomics though. These are socio-cultural concepts. So they should stick their PhD where it belongs and address the arguments head on instead of trying to argue from authority.
I don’t have a PhD, but my understanding of the basics is this:
All people start out developing as female in the womb before a certain point where a large dose of testosterone caused (usually) by the Y chromosome activating (basically the only time in life that it does apart from starting puberty AFAIK) causes the proto-labia and vagina to push outwards and form the ball sack and enlarging the clitoris and urethra into what we know of as the penis. This is why you can see that line down the middle of your ball sack; that’s where your labia fused together. It’s also why the tissue that makes up your ball sack is biologically identical to the tissue that makes up the inside of the vagina. It’s an outie vs. an innie.
There are many reasons why this wouldn’t happen “correctly” since biology is more a wonder of things somehow working at all after evolution is done with them rather than a perfectly designed, well-oiled machine. Sometimes the Y chromosome simply doesn’t activate, or it does, but the person has androgen insensitivity and so the testosterone doesn’t do anything, or they develop as female but have testicles where their ovaries should be, rendering them infertile but otherwise a perfectly normal woman. Sometimes a person is XX, but they experienced a higher than normal amount of testosterone during development and developed male instead of female.
And that’s before you get into the issue of intersex people, who are often surgically altered as babies when they’re born by the doctor to match with the genitalia that the doctor thinks should be the “correct” one. In a number of places, the doctors don’t have to ask permission or even tell the parents after.
Also, your definition of cis male is slightly off. “Cis” is the opposite Latin prefix of “trans,” meaning a non-changing/stable state of being, and in this case it’s used to mean that one’s gender identity matches up with the one that you were given at birth. It ultimately has nothing to do with what genitalia you have, and it’s simply an identification saying that your sense of gender matches up with the sex that the doctor declared and that you therefore aren’t trans. It’s an after the fact solution to the question of what to call people who aren’t trans and comes from the use of trans to identify somebody who transitions from one gender to another.
Chemists have moved away from cis and trans partly because of all of this. We use zusammen-together or entgegen-opposite now. I can attest to how politically charged a class about organic molecules can become.
I am not deeply versed on the socio-cultural side of it all, and there is clearly space to learn. I am reluctant to let cis hinge on a doctor’s proclamation but I’ll let it sit there for the moment.
I think you’re misunderstanding the point the OP is making. Typically, male/female are used when referring to sex, and masculine/feminine and man/woman are used when referring to gender. So this conversation isn’t about gender identity at all, but completely about biological sex.
There are a bunch of factors that go into determining sex. The two main categories are related to the person’s genes (their genotype) and how the person physically presents (phenotype). The biggest genetic marker is whether the person has XX or XY chromosomes (or some other combination). The easiest marker for phenotype is the person’s genitalia, but there are others, such as gonads, gamete production, hormones, etc.
So even just talking about biological sex, a person’s genotype and phenotype might give conflicting determinations of sex. So an “XX male” refers to someone with the genotype of a female, but the phenotype of a male, but says nothing about their gender identity or any surgeries they might’ve undergone.
With that in mind, someone with a PhD in genomics seems to be in the right field to address gene expression and genotypes vs phenotypes. Although you’re right that we shouldn’t rely on authority, but instead on the arguments presented. What we’ve been shown here, though, isn’t a fully fleshed out debate. It’s about 60 words on social media that amounts to “your mental model of sex is wrong; here are cases to rebut it”
I also have a PhD. Not in genomics but in physiology. But we all do genetic work now.
The Dr. says that XX persons can become cis men. “CIS men” is explicitly about gender. I was trying to make the point (not very well as it turns out) that all of this hinges on definitions. So you have to unpack CIS men in this context. Without a sound understanding of the basics, all the rest is supposition.
And the gender identity and expression parts have nothing to do with gene expression, penetrance (giggity), DNA, RNA or epigenetic factors in gene expression.
Also the better example for the counter argument would probably be CAIS.
cis just means your current gender identity is the same that was assigned to you at birth. there are cases where someone has XX chromosomes, but the body develops as male.
Maybe she means the exceptions?
Exceptions: While XX and XY are the most common sex chromosome combinations, there are exceptions, such as individuals with variations in their sex chromosomes, such as XXY (Klinefelter syndrome) or XYY.
De La Chappell syndrome, congenital adrenal hyperplasia, androgen exposure in utero, ovotesticular disorder of of sex development all result in a person with cis male characteristics and in some cases cis male typical genitalia despite having xx chromosomes
https://en.wikipedia.org/wiki/XX_male_syndrome
tldr biology is dice rolls and humans are intersex for no reason sometimes
on a side note one of my friends had this and she only found out when she started transitioning. she is now a trans woman with XX chromosomes. i can only imagine how fucking vindicating it must have felt
WTF is going on on that article’s Talk page? Are teachers now assigning students to edit Wikipedia articles and have others “peer review” them?
It seems like it’s a cooperation between Wikipedia and some schools?
https://en.m.wikipedia.org/wiki/Wikipedia:Wiki_Ed/Western/Bio_3595_AdGen_Wikipedia_Project_(Fall)
tldr biology is dice rolls and humans are intersex for no reason sometimes
To make involuntary non-cis , non-het , infertile aunts and uncles.
grammar is not science
It be an art.
grammer be dat
Whoa, look, an artist!
they don’t think it is, but it do.
Art has weight that influences the human psyche. Let the man work.
But linguistics is
It may as well be astrophysics for some people.
you just know that 75% of people who would wear this don’t really have a PhD and 90% of those don’t have a PhD in the right field
I mean look at the brainrot in this very thread
What brain rot do you mean?
Wait until they learn about XXY, XYY, and XO individuals.
There hugs AND kisses people?
We prefer “asexual” or “ace”.
I swear I was learning about extra X and Y in high school 20 years ago and that studies (at the time) were showing correlation between different traits displayed by effected people. Just that alone shows incredible gender fluidity.
So where we are, 20 years later, you’d think we’d have a better understanding within society but instead somehow it’s literally regressed since then.
Note how they always enshrine gender in biology, but then make all kinds of non-biological statements about what gender is.
“XX is woman”/“Large gametes is woman”/“can conceive is woman”
And then they’ll say
“Women aren’t as aggressive”, “women are more emotional”, “women like being in the home more”, “those are women’s clothes”, etc.
The only reason it’s so important for it to be biological is because of how it punishes gender non-conformity and makes the lives of trans people hell. Like it isn’t ideologically consistent and they know that. They just don’t care. If it was just about genitals or chromosomes, then why is it that gender dictates all these social things about us? The only reason to root gender in how you were born is to ensure gender roles are as rigid and immutable as possible.
Aren’t there more than two sexes in biology?
Depends on how you’re counting.
Yes, there are many species that have more than 2 sexes. Those are decided by scientific consensus.
But sex is ultimately a category to describe the process of reproduction. By definition, this is exclusionary. It’s why conservatives fumble so much when trying to describe sex in terms of actual definitions. Inherently, it is not possible to fit every person into a table of 2 columns in that way. Sex is not a binary because human beings are not binary. There is an incredible amount of variation in our bodies.
Relating to humans?
Yes but they are mutations (e. g. XXY, XXX, etc.) that often give rise to numerous biological problems or death.I don’t know if there are species that require more than two sexes to propagate. I never head of them.
You are vastly underestimating the prevalence of chromosomal variations. They are common, especially among cis women.
I like the way you phrased that at the end. Sexes are categories that relate exclusively to the concept of progeny. If you’re not able to reproduce, you’re already kind of excluded from the sex binary. If we break the human concept of sex down to its constituent parts, it is just “can procreate”. The categories are useful in some contexts, but to state them as universal or to try and extrapolate them so widely is significantly disruptive and unhelpful. Humans are and always have been more than our reproductive anatomy. Your doctor and anyone you want to reproduce with are really the only people who need to know whether you fit into either category.
Im thinking creatures that propagate via asexual reproduction might not fit the male/female sex binary and intersex might not as well?
But that’s not more that two sexes. It’s the same number or less. A hermaphrodite isn’t a third sex, it’s two sexes side by side and a sexless cellular organism has exactly one sex.
The distinction male/female is usually determined by measuring the size of the gametes. Female gametes are the bigger ones (e. g. ovum) and male gametes are the smaller ones (e. g. spermatozoon). There are organisms where the gametes of both sexes have the same size. So technically they have two sexes but don’t fit the categories male and female.
But wouldn’t the asexual reproducing animal that is one sex be neither male or female and thus is a third?
Sex in the sense that we have been talking about it here is in reference to mammals. The moment you wander outside of the mammalian class of vertebrates these concepts of sex start to become far less applicable.
There are many birds that have more than 2 sexes. Reptiles and invertebrates as well. Asexual reproduction would be classed as it’s own sex apart from any male/female system.
you’re a mammal though right
Correct on both counts. To make it even better, there exist some creatures that primarily mate and reproduce sexually, but can also reproduce asexually if the situation requires it - I think ants, and some reptiles, if I remember right.
XY is a mutation, genius
The only reason to root gender in how you were born is to ensure gender roles are as rigid and immutable as possible.
This, this right here, that’s the game, that’s the whole game. They want to punish transness and then start changing what the definition of trans is.
“Your daughter was wearing pants, and said no when my boy asked her out, that’s trans behavior and it’s unAmerican, might have to report you to a correction agency if this shit doesn’t stop.”
how it punishes
gendernon-conformityFit the mold or die. Always the same.
Without a purity test how can I tell which members of the tribe are loyal and which might betray me?
Does it float?
While this is very funny, and definitely representative of a sort of ignorance/arrogance commonly found in ideologues - I recently learned that most people talking about the effect have, in fact, been Dunning-Krugering themselves.
Insightful video on the topic.
What most people expect the effect to look like:
What the actual results were:
Fig 1 is a modified emotional change curve applied in learning and business settings. The term “Valley of Despair” is used in both concepts, and it’s cool, memorable verbiage, but it shouldn’t imply relation between Dunning-Kreuger and the change curve
Image description: A modified emotional change curve from Evocon with Y-Axis being “attitude during change process” and X-Axis is time. There are 6 emotional phases described on this chart: 1. Neutral attitude, no knowledge; 2. Initial excitement, motivated; 3. Denial, indifferent, passive, apathy; 4. Resistance, frustration, doubt, anxiety (this phase falls below neutral and is described as “The Valley of Despair”); 5. Exploration, energized, small wins, creative; 6. Commitment, enthusiasm, problem solving, focus, team work.
Yeah, it’s really frustrating and quite ironic that pop culture keeps using this obscure scientific reference, that they don’t really understand in its intended context, to describe something that really ought be plainly said: that we all have a tendency to overinflate our competence. if anything Dunning-Krueger showed that only the most seasoned experts judge themselves modestly. (and even then we’d likely only find their modesty in that particular area of expertise). it’s a commentary on all of us!
But no, people name-drop this research just to dunk on people and feel smugly superior. (and I am glad I agree with the politics of the intellectual in the OP, that means it’s okay and I’m a bit more competent too!) ugh. I cringe every time i read someone say Dunning-Krueger.
PS on your first image, whoever failed to put “phd student” at the trough of that curve fucked up
While I know of the proper dunning-kruger effect chart, that still doesn’t help me out of the imposter syndrome valley of despair
How do you know if someone has a PhD.?
They tell you
Never not true
How do you know someone has a PhD?
When it becomes acutely relevant, they’ll politely let you know, and then you can become annoyed at them about it.
Thinking about it, that exact thing also applies to other ‘how do you know someone is/has/does […]’ as well.
I mean yeah, if you spent 5 years of your life pushing the edge of human understanding on a subject, and a shithead tells you to do the science on your research subject, it’s relevant lol
…why shouldn’t they?
Sometimes they don’t tell you and just quietly update all of their usernames…
Do you by chance have a PhD in food science?
Tacology
Right? It’s really weird…
Well you don’t know people with PhD that don’t tell you they have one
An unknown-unknown?
Tbf, they kinda earned the right to brag.
I never tell people I have a PhD. It’s rude, plus I don’t have one.
This is putting confirmation bias to the extreme.
True, but I do think it was warranted in this case.
Funny enough, my boss has a PhD in Evolutionary Biology. She never tells people because they start referring to her as Doctor, and she hates that. I don’t think I’ve actually ever heard her bring it up on her own.
Can I get a T shirt that says “I have Dunning-Krueger and your Phd looks cute”? I just have a lot of BS to share and I don’t want to be sorry about it.
Dunning-Krueger effect is the delusion that you are smarter than a serial killer who stalks teenagers in their nightmares.
Actually, the science says you will feel regret and will grow to resent that shirt over time. /s
That’s because today’s t-shirts are made of such poor materials.
But the economics says I should print them and make a fortune selling them to idiots. Hmm decisions, decisions.
I’m a bit uninformed on this; it seems fascinating. Do these things happen due to something unusual during the growth of a fetus? What’s the name for this phenomenon?
There’s a bunch of them, but one more common example is Androgen Insensitivity Syndrome.
It’s also possible to have a non-functional SRY (XY but female), or to be XX with an SRY translocation (XX but male).
Biology is complicated: pretty much anyone who says it only happens one way or is really simple is wrong.
“Yeah… SRY, but sex and gender are not a binary.”
Moron here: Are XY females sterile or is it possible for them to pass on the Y, along with a male partner Y gene to give the baby YY genes? Or is this combination non-viable and wont develop?
YY is non viable; the X chromosome has many genes which are essential. You can be XY, female, and fertile, but it’s pretty rare.
Mothers always pass the X chromosome due to how the egg works from what I remember. The sperm determines whether you get x or y for the second part.
There is a rare event where you can have multiple sex chromosomes, like XYY, but the X is always present (at least for humans). Considering the genes in an X chromosome are vital to life, even if we could artificially create YY, it would probably end up nonviable
XY females aren’t always sterile! Most of the cases we know of are sterile though, because you don’t get tested for this stuff unless something’s wrong (the woman in the case study got tested because XY women are common in her family, her daughter is XY).
You know how a bunch of villains are Dr. So-and-So? I bet it’s dealing with morons talking about your area of expertise that leads to one’s villain era.
“That’s doctor Evil. I didn’t spend 8 years in evil medical school to be called mister, thank you very much.”
I was once the hero now I am the villain
Honestly, it would be a pretty lame T-shirt.
Critically thinking now, how strong is the evidence here?
My take is that sex-linked characteristic are grouped together due to prehistoric and historic evolution. Since I dont have a womb my tits would not have been worth the energy cost in an ancestral environment. Therefore, they are not coded in my DNA and I have to dose to maintain them.
There are people who are different, that is a fact.
Some folks are given “PhD”, others are kidnapped and sent to concentration camps. Is the education system legitimate, or corrupted by authority?
A person’s biological sex usually refers to their status as female or male depending on their chromosomes, reproductive organs, and other characteristics. Chromosomes are tightly packed DNA, or molecules that contain the genetic instructions for the development and functioning of all living things. Humans typically have forty-six chromosomes. Two of those are sex chromosomes that contain instructions for the development and functioning of characteristics related to biological sex, such as reproductive organs. There are two kinds of human sex chromosomes, X and Y. Individuals identified as males tend to have one X and one Y chromosome, while those identified as females tend to have two X chromosomes. However, other people are born with other chromosome combinations, such as XXY, that lead them to develop a mix of characteristics. People who fit that description are often referred to as intersex, a category for people whose bodies do not conform with stereotypical expectations of males or females at birth.
Taken from here
Evidence seems pretty strong to me.
Yeah, and those are malformations and genetical defects that come with a lot of problems.
I don’t know why people glorify them… Also, there is absolutely no way that a man born with XY magically will change it in their lifetime as the posts sugests.
The post suggests that some people with XY chromosomes are assigned female at birth and will live as a woman.
And some people with XX chromosomes are assigned male at birth and will live as a man.
Not that the chromosomes change.This article seems to disagree. But I don’t know much on the subject so I might be misunderstanding.
Also, no matter what the correct answer is, pretending the answer is binary is definitely wrong. Since it’s obviously a lot more complicated.
From the article:
“Girls born with XY chromosomes are genetically boys but for a variety of reasons – mutations in genes that determine sexual development”
And again, they don’t magically become the other sex, that was already determined at birth.
No, not magically, no. You’re right.
Well, to be fair, not magically and not in any other way, it is impossible to change your sex
You’re the only one talking about this. A change can occur without any surgery. Reread the article to understand better, please.
You read the article and you even quoted it. It says how xx people can be men and how xy people can be women. Nobody said anything about any surgery or magic pill that grows a penis or whatever you’re imagining.
Those are two real medical diagnoses - Swyer syndrome or XY gonadal dysgenesis for XY women (occurs in about 1:100000 women) and de la Chapelle syndrome or XX male syndrome for XX men (occurs in about 1:20000 to 1:30000 men)
Here is a NORD report on Swyer syndrome, as well as the original article on de la Chapelle syndrome: 1.https://rarediseases.org/rare-diseases/swyer-syndrome/ 2.https://pmc.ncbi.nlm.nih.gov/articles/PMC1762158/
