Thoraiya DyerGenetic Screening – Is It Value For Money?
May 27th 2008 22:05
Have you ever wanted to peep into your own biological blueprint?
Thought you’d have to see a raft of medical specialists? Well, that was before DNA analysis became available in “home test kit” packages, direct from laboratory to you.
Are they for real, or just another scam for us to avoid?
Summarised nicely by Medline ( Really Long Link ), genetic tests are defined as follows:
“Genetic tests are tests on blood and other tissue to find genetic disorders. About 900 such tests are available. Doctors use genetic tests for several reasons. These include:
a) Finding possible genetic diseases in unborn babies
b) Finding out if people carry a gene for a disease and might pass it on to their children
c) Screening embryos for disease
d) Testing for genetic diseases in adults before they cause symptoms
e) Confirming a diagnosis in a person who has disease symptoms
People have many different reasons for being tested or not being tested. For many, it is important to know whether a disease can be prevented or treated if a gene alteration is found. In some cases, there is no treatment. But test results might help a person make life decisions, such as career choice, family planning or insurance coverage. A genetic counselor can provide information about the pros and cons of testing.”
All good reasons to send a scraping of your cheek cells to a lab? Why do you need a genetic counselor? You either have the gene for something or you don’t, right?
Actually, no.
Not all diseases with a genetic basis are created equal.
Helen O’Neill, in her article “Estimating Disease Risk With Genetic Screening,” ( Really Long Link ) explains that,
“All somatic cells in an individual carry genes from both the mother and the father and these are inherited en bloc on chromosomes. The human cell has 23 different chromosome pairs including an XX pair of sex chromosomes in females and an XY pair in the male. The approximately 30 000 genes carried by the 46 chromosomes represent the human genome.”
Clear so far? If a gene is a page of information, then chromosomes are the books. Or, rather, they are encyclopedias, numbered from 1 to 22, and you need two versions of each volume. Generally, if there’s a page ripped out or scribbled on in Mum’s book, the equivalent page in Dad’s book will be normal, and you will turn out OK.
Right. So you get books 1 to 22 from Mum (plus book X) and another set of books 1 to 22 from Dad (plus either another book X or a book Y), giving you 46 books in your own unique little library.
What happens if there’s an error and you get THREE copies of book 21, instead of two?
The University of NSW tells us:
“Down Syndrome or trisomy 21 … is one of the most common chromosomal abnormalities in liveborn children. The frequency of trisomy 21 in the population is approximately 1 in 650 to 1,000 live births, in Australia between 1991-97 there were 2,358 Trisomy 21 (Down) infants.”
That’s something you can screen for pretty easily. Take a cell, get the chromosomes out, and count them:
Well, it’s not that easy. Actually, it’s really amazing, and my hat’s off to all researchers in genetics.
For all their hard work, there isn’t really that much money to be made by figuring out things like BlahBlah Gene is responsible for the formation of BlahBlah protein on the surface of BlahBlah cell in the liver.
According to payscale.com.au, a Research Scientist in Sydney, NSW, with 10 years experience in biotechnology R & D can expect to be paid an annual salary of $60k.
Meanwhile, a quick search on CareerOne reveals that a Senior Project Manager in the same city can expect $160k for overseeing the construction of a road.
So it’s no wonder laboratories are trying to make a quick buck on the side with home testing kits. Must be tempting – even if it IS a load of crapola when it comes to diseases more tricksy than trisomy 21.
Helen O’Neill makes the point that even if “More than 1000 human disorders have a genetic component”, “very few (~100) of these are caused by single gene defects.”
“The majority of diseases with a genetic component are complex diseases involving somewhere between 10 and 30 different genes.”
One of those diseases is obesity.
According to Katrina A.B Goddard of the American CDC ( Really Long Link ),
“Approximately 30% of US adults are now obese (Body Mass Index (BMI)≥30 kg/m2) [Hedley et al., 2004], representing a significant health problem in the US and other developed countries…Although lifestyle factors, such as diet and exercise, are important determinants of obesity, genetic studies have produced estimates of heritability for BMI between 30-70% [Bell et al., 2005; Farooqi et al., 2005; Hebebrand et al., 2003; Schousboe et al., 2003].”
Clearly, genetics plays a role in the likelihood of someone becoming overweight. But has anyone pinned down the gene or genes responsible?
“In April 2006, Herbert et al. reported that a common variant near the insulin-induced gene 2 (INSIG2) is associated with obesity… The high-risk genotype is present in approximately 10% of the population, and confers a risk approximately 1.22-1.33 times the risk among persons without the high risk genotype.
Well, that’s the sort of thing that would make news headlines like “Herbert discovers fat gene.” But if we read it again, we discover that 30% of Americans are obese, yet only 10% of them have the risky gene.
In at least two thirds of obesity cases, then, the “fat gene” variation of INSIG2 is nowhere to be seen.
Besides that, the risky gene only makes you 22 – 33% more likely to get fat than anyone else. So around 70% of people with the risky gene aren’t even going to be at risk.
Worth screening for?
I really don’t think so.
But wait. Athena Diagnostics (athenadiagnostics.com) promised me it could test me for the fat gene! That way, when I fail to control my own eating habits, I can blame all my problems on my genes. And as soon as they find out, my loving parents can “emphasize the necessity to work with the child on limiting his or her food intake.”
Shouldn’t they be doing that anyway, if I’m square and lardy by the age of six?
Athena screens for “Early Onset Obesity” by looking for a completely different fat gene – instead of INSIG2, they look for a mutation in MCR4. A quarter of American children are fat, it says, and ten percent of those fat children are scarily, horribly fat (“obesity can be considered severe”.)
In 5% of the scarily, horribly fat children, there’s something dodgily wrong with MCR4.
Now, let’s see. Whipping out my trusty calculator, it seems that 5% of 10% of 25% equals 0.125% of American children who have this mutant gene.
In other words, 99.5% of fat children do NOT have it.
Worth screening for?
Hell, no! Chances are you’re just giving him too many twinkies and hot dogs! *Arnold Schwarzenegger voice* STOP IT!
And don’t let me forget GeneOb ( http://www.geneob.com/ ), which offers to,
“…help people manage their weight by assessing their genetic predisposition and developing tailored diet and exercize programs.”
…yet, on its Scientific facts page, it doesn’t say which gene variations it screens for; only warbles about the genes responsible for susceptibility to breast cancer.
Interestingly, when we check the info page, we find this:
“E. Murray is an assistant professor at the highly reputable School of Business, Queen's University. She has received numerous academic awards and homours, and has published several articles on various subjects such as strategic management. Elspeth Murray is an authority on linking information technology strategy and business strategy.”
AND this:
“Maria Luckevich is a business consultant specializing in new ventures in biotechnology.”
Setting up opportunistic marketing types within laboratories must be quite profitable. After all, says the United States Department of Health and Human Services ( Really Long Link ),
“The number of genetic tests performed each year is growing dramatically. A recent survey of genetic testing laboratory directors found that between 1994 and 1996, the total number of tests performed by laboratories grew by at least 30 percent each year, rising from 97,518 in 1994 to 175,314 in 1996. And the rate of increase continues to grow.”
Maybe one day, all 30 (or 40 or 50) genes which have a role to play in obesity will be discovered, and a meaningful test will be developed. But that time is not yet. Realistically, it will not be until the function of ALL 30 000 human genes is known.
In a paper entitled “Tests Purchased From Four Websites Mislead Consumers,” ( Really Long Link ) the United States Government Accountability Office found in July 2006 that,
“The results from all the tests GAO purchased mislead consumers by making predictions that are medically unproven and so ambiguous that they do not provide meaningful information to customers.”
This investigation was delightfully sneaky, and it’s well worth a read. Basically, they sent the same DNA for analysis (a cheek swab from a 9 month old baby girl) to all the different labs, but with different fictitious stories attached.
Sadly, the cat and dog DNA they submitted did not fool the labs (“could not be processed”). But I’m laughing just thinking about it and I wish the Chasers would take up the challenge.
The GAO goes on to say that two of the four labs recommended “personalised” dietary supplements worth around $1200, one of which was a $1880 product supposed to “repair DNA” (a load of unsubstantiated baloney, as you might have guessed). Most gave “personalised” dietary advice that was just normal, healthy eating advice.
I suppose if people paid a thousand dollars for advice like that from a laboratory, they’d be more likely to actually do what it said: quit smoking, exercise, and eat more fresh fruit and vegetables.
But that advice is available for free, no matter what’s in your genes. No analysis was necessary.
The US Federal Trade Commission ( Really Long Link ) offers some healthy, sceptical advice for those considering genetic testing:
“...some of these tests lack scientific validity, and others provide medical results that are meaningful only in the context of a full medical evaluation. The FDA and CDC say that because of the complexities involved in both the testing and the interpretation of the results, genetic tests should be performed in a specialized laboratory, and the results should be interpreted by a doctor or trained counselor who understands the value of genetic testing for a particular situation.”
Please, see your doctor if pain persists.
Thought you’d have to see a raft of medical specialists? Well, that was before DNA analysis became available in “home test kit” packages, direct from laboratory to you.
Are they for real, or just another scam for us to avoid?
Summarised nicely by Medline ( Really Long Link ), genetic tests are defined as follows:
“Genetic tests are tests on blood and other tissue to find genetic disorders. About 900 such tests are available. Doctors use genetic tests for several reasons. These include:
a) Finding possible genetic diseases in unborn babies
b) Finding out if people carry a gene for a disease and might pass it on to their children
c) Screening embryos for disease
d) Testing for genetic diseases in adults before they cause symptoms
e) Confirming a diagnosis in a person who has disease symptoms
People have many different reasons for being tested or not being tested. For many, it is important to know whether a disease can be prevented or treated if a gene alteration is found. In some cases, there is no treatment. But test results might help a person make life decisions, such as career choice, family planning or insurance coverage. A genetic counselor can provide information about the pros and cons of testing.”
All good reasons to send a scraping of your cheek cells to a lab? Why do you need a genetic counselor? You either have the gene for something or you don’t, right?
Actually, no.
Not all diseases with a genetic basis are created equal.
Helen O’Neill, in her article “Estimating Disease Risk With Genetic Screening,” ( Really Long Link ) explains that,
“All somatic cells in an individual carry genes from both the mother and the father and these are inherited en bloc on chromosomes. The human cell has 23 different chromosome pairs including an XX pair of sex chromosomes in females and an XY pair in the male. The approximately 30 000 genes carried by the 46 chromosomes represent the human genome.”
Clear so far? If a gene is a page of information, then chromosomes are the books. Or, rather, they are encyclopedias, numbered from 1 to 22, and you need two versions of each volume. Generally, if there’s a page ripped out or scribbled on in Mum’s book, the equivalent page in Dad’s book will be normal, and you will turn out OK.
Right. So you get books 1 to 22 from Mum (plus book X) and another set of books 1 to 22 from Dad (plus either another book X or a book Y), giving you 46 books in your own unique little library.
What happens if there’s an error and you get THREE copies of book 21, instead of two?
The University of NSW tells us:
“Down Syndrome or trisomy 21 … is one of the most common chromosomal abnormalities in liveborn children. The frequency of trisomy 21 in the population is approximately 1 in 650 to 1,000 live births, in Australia between 1991-97 there were 2,358 Trisomy 21 (Down) infants.”
That’s something you can screen for pretty easily. Take a cell, get the chromosomes out, and count them:
The image above shows isolated chromosomes from a male trisomy 21 (red arrow shows extra chromosome 21).
Well, it’s not that easy. Actually, it’s really amazing, and my hat’s off to all researchers in genetics.
For all their hard work, there isn’t really that much money to be made by figuring out things like BlahBlah Gene is responsible for the formation of BlahBlah protein on the surface of BlahBlah cell in the liver.
According to payscale.com.au, a Research Scientist in Sydney, NSW, with 10 years experience in biotechnology R & D can expect to be paid an annual salary of $60k.
Meanwhile, a quick search on CareerOne reveals that a Senior Project Manager in the same city can expect $160k for overseeing the construction of a road.
So it’s no wonder laboratories are trying to make a quick buck on the side with home testing kits. Must be tempting – even if it IS a load of crapola when it comes to diseases more tricksy than trisomy 21.
Helen O’Neill makes the point that even if “More than 1000 human disorders have a genetic component”, “very few (~100) of these are caused by single gene defects.”
“The majority of diseases with a genetic component are complex diseases involving somewhere between 10 and 30 different genes.”
One of those diseases is obesity.
According to Katrina A.B Goddard of the American CDC ( Really Long Link ),
“Approximately 30% of US adults are now obese (Body Mass Index (BMI)≥30 kg/m2) [Hedley et al., 2004], representing a significant health problem in the US and other developed countries…Although lifestyle factors, such as diet and exercise, are important determinants of obesity, genetic studies have produced estimates of heritability for BMI between 30-70% [Bell et al., 2005; Farooqi et al., 2005; Hebebrand et al., 2003; Schousboe et al., 2003].”
Clearly, genetics plays a role in the likelihood of someone becoming overweight. But has anyone pinned down the gene or genes responsible?
“In April 2006, Herbert et al. reported that a common variant near the insulin-induced gene 2 (INSIG2) is associated with obesity… The high-risk genotype is present in approximately 10% of the population, and confers a risk approximately 1.22-1.33 times the risk among persons without the high risk genotype.
Well, that’s the sort of thing that would make news headlines like “Herbert discovers fat gene.” But if we read it again, we discover that 30% of Americans are obese, yet only 10% of them have the risky gene.
In at least two thirds of obesity cases, then, the “fat gene” variation of INSIG2 is nowhere to be seen.
Besides that, the risky gene only makes you 22 – 33% more likely to get fat than anyone else. So around 70% of people with the risky gene aren’t even going to be at risk.
Worth screening for?
I really don’t think so.
But wait. Athena Diagnostics (athenadiagnostics.com) promised me it could test me for the fat gene! That way, when I fail to control my own eating habits, I can blame all my problems on my genes. And as soon as they find out, my loving parents can “emphasize the necessity to work with the child on limiting his or her food intake.”
Shouldn’t they be doing that anyway, if I’m square and lardy by the age of six?
Athena screens for “Early Onset Obesity” by looking for a completely different fat gene – instead of INSIG2, they look for a mutation in MCR4. A quarter of American children are fat, it says, and ten percent of those fat children are scarily, horribly fat (“obesity can be considered severe”.)
In 5% of the scarily, horribly fat children, there’s something dodgily wrong with MCR4.
Now, let’s see. Whipping out my trusty calculator, it seems that 5% of 10% of 25% equals 0.125% of American children who have this mutant gene.
In other words, 99.5% of fat children do NOT have it.
Worth screening for?
Hell, no! Chances are you’re just giving him too many twinkies and hot dogs! *Arnold Schwarzenegger voice* STOP IT!
And don’t let me forget GeneOb ( http://www.geneob.com/ ), which offers to,
“…help people manage their weight by assessing their genetic predisposition and developing tailored diet and exercize programs.”
…yet, on its Scientific facts page, it doesn’t say which gene variations it screens for; only warbles about the genes responsible for susceptibility to breast cancer.
Interestingly, when we check the info page, we find this:
“E. Murray is an assistant professor at the highly reputable School of Business, Queen's University. She has received numerous academic awards and homours, and has published several articles on various subjects such as strategic management. Elspeth Murray is an authority on linking information technology strategy and business strategy.”
AND this:
“Maria Luckevich is a business consultant specializing in new ventures in biotechnology.”
Setting up opportunistic marketing types within laboratories must be quite profitable. After all, says the United States Department of Health and Human Services ( Really Long Link ),
“The number of genetic tests performed each year is growing dramatically. A recent survey of genetic testing laboratory directors found that between 1994 and 1996, the total number of tests performed by laboratories grew by at least 30 percent each year, rising from 97,518 in 1994 to 175,314 in 1996. And the rate of increase continues to grow.”
Maybe one day, all 30 (or 40 or 50) genes which have a role to play in obesity will be discovered, and a meaningful test will be developed. But that time is not yet. Realistically, it will not be until the function of ALL 30 000 human genes is known.
In a paper entitled “Tests Purchased From Four Websites Mislead Consumers,” ( Really Long Link ) the United States Government Accountability Office found in July 2006 that,
“The results from all the tests GAO purchased mislead consumers by making predictions that are medically unproven and so ambiguous that they do not provide meaningful information to customers.”
This investigation was delightfully sneaky, and it’s well worth a read. Basically, they sent the same DNA for analysis (a cheek swab from a 9 month old baby girl) to all the different labs, but with different fictitious stories attached.
Sadly, the cat and dog DNA they submitted did not fool the labs (“could not be processed”). But I’m laughing just thinking about it and I wish the Chasers would take up the challenge.
The GAO goes on to say that two of the four labs recommended “personalised” dietary supplements worth around $1200, one of which was a $1880 product supposed to “repair DNA” (a load of unsubstantiated baloney, as you might have guessed). Most gave “personalised” dietary advice that was just normal, healthy eating advice.
I suppose if people paid a thousand dollars for advice like that from a laboratory, they’d be more likely to actually do what it said: quit smoking, exercise, and eat more fresh fruit and vegetables.
But that advice is available for free, no matter what’s in your genes. No analysis was necessary.
The US Federal Trade Commission ( Really Long Link ) offers some healthy, sceptical advice for those considering genetic testing:
“...some of these tests lack scientific validity, and others provide medical results that are meaningful only in the context of a full medical evaluation. The FDA and CDC say that because of the complexities involved in both the testing and the interpretation of the results, genetic tests should be performed in a specialized laboratory, and the results should be interpreted by a doctor or trained counselor who understands the value of genetic testing for a particular situation.”
Please, see your doctor if pain persists.
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