Thanks to identical twins, we might be able to detect breast cancer before it even develops

Scientists practically drool over identical twins and their shared DNA, especially when one twin develops a major, and possibly genetically related illness, and the other does not. Identical twins can help unlock medical mysteries that might otherwise go unsolved.
The results of a recent study on breast cancer can help the rest of us appreciate the scientific fever over identical twins and their potential contributions.
This is a big one.
The study -- led by Manel Esteller, director of the Cancer Epigenetics and Biology Program at the Bellvitge Biomedical Research Institute (IDIBELL), Professor of Genetics at the University of Barcelona and ICREA researcher -- has helped researchers identify a genetic change that occurs in those who will later develop breast cancer.
This information could lead to new blood tests that help doctors identify breast cancer victims long before their cancers actually develop. It could lead to new drugs that more efficiently target tumors and that prevent breast cancer in the first place.
It all goes back to epigenetics.
All DNA is influenced by environment.
Chemical signals received by DNA can trigger certain changes, turning genes off and on like a light switch. That's the theory behind epigenetics. It's why some pairs of identical twins have clear physical differences, like height or moles or head shape. It explains lower immunity in one twin than in another. It shows why some will develop certain genetic diseases while their twins do not.
In this case, researchers found that twins with breast cancer had "a pathological gain of methylation in the DOK7 gene" years before their cancer was clinically diagnosed, according to Dr Esteller in an article on the institute's website.

The next step for the researchers will be knowing the exact function of the DOK7 gene. "We believe it is a regulator of tyrosine kinases, an antitumor drug target already used for the treatment of breast cancer. If DOK7 performs this function, new studies to test drugs with tumour chemopreventive effects in breast cancer could be planned in the future," he concludes.

In simpler terms, scientists believe that particular gene is a regulator of a drug already used to fight tumors. If that proves true, the information could lead to big changes in the way we diagnose, treat and prevent breast cancer.  A simple blood test could tell women (And men. Let's not forget they can have breast cancer too.) whether they will develop the disease in the near future.
All thanks to 36 sets of selfless identical twins.

The evidence is in: differentiation in identical siblings begins before birth

The medical community has finally confirmed something most all parents of identical twins have always known: Our twins do not emerge from the womb purely identical. Differentiation begins when the egg splits and continues throughout their lifetimes.
Identical twins share the same DNA.
This new study does not dispute that.
Rather, the explanation for the differences lies in epigenetics, the way identical genes that accompany that shared DNA express themselves. Genes, scientists have learned, can be turned on and off like light switches. Those switches are flipped by environmental influences.
Epigenetics explains why identical twins can look somewhat different and have different inheritable diseases and conditions despite their common DNA.
I see it in my own guys.
At 5 years old, Matthew and Jonathan are precisely the same height. Their hands and feet are the same sizes and their hair grows in all the same directions. Yet, one is slighter than the other, overall. One has a higher-pitched voice. One has a spider vein on his face.
They have different tastes in food and different levels of immunity.
They are daring in different ways; shy in different ways.
They are very much identical, but they are different.
Before we had Jonathan and Matthew DNA tested, when they were still infants, so many people looked for those minute differences as proof that they were fraternal. Identical twins, especially infants, should be identical in every way, they believed.
It was annoying.
Some of those people were relentless.

Scientists had already proven such changes take place after birth, but researchers from Murdoch Children’s Research Institute (MCRI) in Melbourne are the first to prove the environment in utero can also be responsible for such changes.
The Australian scientists used cord blood, placentas and umbilical cords collected at birth from both identical and nonidentical twins to prove their theories, according to recent article in the Deccan Herald. They found that although identical twins share the same DNA sequence, the chemical markers that switch genes on and off are different.
That makes sense to me.
In that first ultrasound at 20 weeks, the day we learned I was carrying twins, Matthew was already set to escape. He had claimed the spot at the bottom of my uterus near the cervix, the head-down position usually reserved for a baby who is prepared to make an exit.
There he remained until delivery.
Jonathan seemed to spend the whole pregnancy trying to get comfortable. He was in breech position at delivery after flipping head-up and head-down a few times during the last weeks of pregnancy (That hurts, by the way!). When Matthew cleared out his space, Jonathan spent the next 20 minutes swimming, alluding the grip of my OB.
He became a c-section baby when he decided to take a pike dive -- head and foot first -- into the world.
Their experiences in utero were entirely different.
Why wouldn't that change them?
What does that mean for identical siblings? For parents of identical siblings?
It's hard to say.
The research team believes it might help track and treat diseases earlier in life. I'm not so sure about that. I can't imagine pediatricians will suddenly start testing the cord blood of all newborns for changes in chemical markers. It's not practical.
Their team leader also noted that it might help parents understand that certain elements of fetal development are out of the parents' control. That could be comforting for some. Disconcerting for others.

For me, personally, it's a scientific answer to questions I get all the time: how can Matthew and Jonathan have physical difference and still be considered identical? It's a scientific answer for all those parents who ask on online forums how their twins might possibly be identical when their birth weights are so drastically different or they are different heights.
It's a scientific answer to support what should be common sense.
No two people will ever be precisely alike.

Finally we have proof! Doctors often misinform parents about zygosity

Throughout my pregnancy, my OB and the ultrasound technician told us our boys were absolutely, positively, no-doubt-about-it fraternal. Yes, my doctor said, identicals can have separate placentas and sacs, but mine implanted too far apart to be identical.
Their placentas were on polar opposite sides of the uterus.
Identical twins implant more closely, he said.
He was wrong.
And he has company.
In a new study from University College London, researchers found that doctors wrongly told parents their identical twins were fraternal in 27.5 percent of the cases. Like my guys, those twins had their own sacs and placentas.
The study also found that 2 percent of parents were wrongly told their fraternal twins were identical because doctors did not realize their separate placentas had fused into one. Overall, 15 percent of twin parents were misinformed about zygosity.
I have long suspected the statistics involving identical twins are skewed.
This proves it.
So many parents find out long after birth that their twins are identical through DNA testing. That information is never reported to any statistic-gathering source. If this study hold true in the US, then statistics showing the odds of having identical twins is about 3 in 1,000 are way off.
It has become a game on online twin forums: Guess whether the twins are identical while the parents await results of DNA testing. In most every case where parents of di/di had trouble telling their twins apart, the results showed they were, indeed, monozygotic, or identical.
I have come across just as many parents of look-alike twins in real life and virtually who decline testing despite their gut feelings. Either they can't afford the $100 to $200 fee or they see slight differences between their twins and accept those as evidence their twins are fraternal.
We could have done that do that with our guys.
Matthew has a slighter build and a thinner face. Jonathan is much more muscular and has a rounded face -- a little more body fat in his cheeks. But that scenario is true of most identicals. One usually has a slightly different facial shape than the other.
In some of those cases, parents brushed off their identical suspicions because their hospitals "tested" the placentas and the results showed they were dizygotic, or fraternal.
Our own doctor fell for that until I pressed him for more information and he checked with the hospital.
It turns out hospitals check only whether placentas are fused. The hospital techs either definitively declare the zygosity according to the results or the pass the results on to doctors or midwives who were told in medical school that two placentas equals fraternal.
The doctors or midwives then pass that misinformation on to parents.
Remember this: hospitals DO NOT do DNA testing.
In the defense of OBs, midwives and ultrasound technician, zygosity is irrelevant in caring for pregnant women. What matters is only whether there is one placenta or two, and one sac or two. So they really don't need to know for medical purposes.
That doesn't, however, excuse the giving of misinformation.
In our case, a fellow soccer mom who was a neonatologist educated me.
She told me that identical twins implant separately when the split occurs immediately after conception -- within the first few days. Matthew and Jonathan probably became two far up in the fallopian tube, she said, allowing them to fall and implant independently, just like fraternal twins.
At the very least, our OB should have told us he didn't know.
He should have known that he didn't know.
All doctors, midwives and ultrasound technicians should know that they can't be certain with same-gender twins until after the babies are born. Though the information is medically irrelevant during pregnancy, there is no excuse for being misinformed about something so relevant to the field in general or for passing that information on to parents.
None.

Sick and sicker: immunity differences in identical twins

Jonathan and Matthew developed colds a while back.
Jonathan is on the mend now, racing the dog from the dining room through the kitchen, eating like a teenager and jumping from the sofa to the floor over and over and over again, ignoring my demands that he stop.
He's driving me crazy.
Matthew is curled up on another sofa, covered with a blanket and watching TV through half-opened eyes. It breaks my heart to watch him hold his ribs when hacking coughs overtake his body. I can't wait for the antibiotics to do their stuff.
He has walking pneumonia.
This medical inequity is nothing new.
A few weeks ago, Jonathan developed a fever that lasted for two days. Matthew caught the same virus, but his fever continued for seven days. A stomach bug that left Jonathan slightly dehydrated for a day as a baby left Matthew with bleeding ulcers and a month's prescription of Zantac.
When Jonathan develops an ear infection, Matthew often gets it in both.
My immediate reaction was to surmise that somehow, when the egg split, Matthew lost an immunity gene to Jonathan. It made sense. Matthew's always been sicker and he was born lighter, slighter, a bit more frail than his brother.
But I came to a different conclusion after doing a little research.
Recent studies are finding that epigenetics -- or the way in which genes express themselves in different environments -- is likely responsible for many differences that develop in identical twins, particularly when it comes to immunity.
Sometime after conception, either in the womb or outside it, one of the twins was likely exposed to a virus or bacteria that missed the other. In fighting off the intruder, he either gained any army (Jonathan), strengthening his physical fortress, or lost one (Matthew), weakening his defenses.
Their identical genes learned to express themselves in different ways when confronted by bacterial infections or viruses, resulting in permanently different immune systems.
Amanda Carpenter, a virology student, writes about an excellent example here. Identical twins born in 1983 were exposed to HIV, the virus that causes AIDS. Fifteen years later, one was relatively healthy and strong while the other was sickly and ill.
After studying blood samples from the pair, researchers concluded that environment, which led to a depressed immunity system in one twin, was likely to blame for their different reactions. Their shared DNA did not ensure a shared prognosis.
My hope for Matthew is that someday this will turn itself around -- that someday he'll be exposed to something that makes him stronger instead or weaker -- and that Jonathan's immunity will remain unchanged.
Who knows?
Maybe this is the one.
Maybe all that hacking and coughing that kept me up last night, worried that he will choke or stop breathing, is the just influence his genes needs.

Cool facts about identical twins

Check this out.
These are some cool facts about identical twins posted on Nursing Schools. The site is designed for those who want to become nurses, but the blog is one of the most useful, entertaining and easy-to-read medical blogs I've seen yet.
I have reduced the list of 20 facts compiled by blogger Kitty Holman to just those that pertain to identical twins.
Thanks to reader Ken Martin, who works for Nursing Schools for sharing.


1. While most people are only familiar with identical and fraternal twins, there are actually 7 different types of twins. They are: identical, fraternal, half-identical, mirror image twins, mixed chromosome twins, superfecundation, and superfetation. Those other than identical and fraternal can be quite rare.

2. Twins do not have to be born on the same date. In fact, they can be born surprisingly far apart. The longest recorded gap between twin births is 85 days. How does this happen? The simplest explanation comes when one twin is born just before midnight and the other after. In cases where there is a longer gap, it's often because one twin is born early due to complications, while the other is left in the womb to further develop. This is much safer for the second baby and can help improve survival rates.

3. Identical twins have different fingerprints. Some people might think that identical twins are the same right down to those whorls and swirls on their fingerprints, but while identical twins share most of their genetic material, identical fingerprints aren't among them. While the fingerprints may be very similar, on close examination it is possible to tell them apart – much like the twins themselves.

4. About 25% of identical twins are called mirror image twins. This means that they are, in fact, identical, but only in the way that your reflection in a mirror is an identical image of you. For example, if one twin has a mole under her right eye, the other will have it under her left eye. Scientists think this is due to the fertilized egg splitting later than the norm for identical twins, around nine to twelve days after fertilization.

5. Identical twins have almost identical brainwave patterns. The notion that twins think alike just might be true. Research on identical twins shows that they have almost perfectly matching brainwave patterns. Some think this could explain twins' abilities to know what the other is thinking and feeling.

6. Twins can celebrate their twinning in Twinsburg, Ohio. (Blogger's note: the 2011 Twins Days festival is scheduled for Aug. 5,6 and 7.) If you or your children are twins, you can head to this city in Ohio to celebrate the Twins Days festival. You'll be amid a sea of look-alikes, with twins, triplets and multiples from all over the nation converging on this town to celebrate being a twin.

7. Twins often develop their own language. This phenomena is called idioglossia. It's something that has fascinated people about twins for years, but it's really a relatively simple and easily understandable process. It happens when one twin models the disordered or incorrect speech of the other, leading to both twins using the same grammatical or speech sound errors. It sounds like a foreign language, but is really just a normal part of cognitive development.

8. Identical twins can be of different sexes. It might sound strange to stay that identical twins can be different when it comes to gender, but technically speaking it is possible. It happens when the egg splitting process doesn't happen quite as it should, resulting in twins that display genetic abnormalities like Klinefelter's syndrome. This means one twin might have the right correlation of XX or XY while the other has XXY.

9. Twins share DNA, but it is not identical. While identical twins come from the same sperm and egg, their DNA isn't necessarily identical, according to new research. Scientists used to think differences in twins were due to environmental factors; they now know that isn't the only force causing variations. Genetic studies have demonstrated that there are certain points where twins will veer away from one another, with one carrying different or multiple copies of the same gene.

10. Fraternal twinning is genetically predisposed. Identical twinning is random. (Blogger's note: recent studies suggest that an inherited enzyme in the sperm combined with a genetic weakness in the egg is responsible for identical twinning.) Fraternal twinning is the result of a woman releasing multiple eggs at the same time, and is largely the result of a genetic predisposition to release this extras. Identical twins, however, are the result of a random split of a single egg, something which cannot be genetically predisposed. In recent years, the number of fraternal twins has risen in response to fertility treatments, while the number of identical twin births has stayed the same.

11. Twenty-seven pounds and 12 ounces is the heaviest combined birth weight of any set of twins. If you think it would be rough to carry around and deliver one 14-pound baby, then imagine doing it with two. That's just what happened in this case, the largest twin birth on record. Of course, it doesn't hold a candle to the largest singleton birth weight of 23 pounds.

12. Twins separated at birth and reunited are often found to be eerily similar in personality and interests. The studies that discovered this fact, however, have widely been condemned as some of the cruelest and morally repugnant in medical history. During the 60's and 70's, identical twins were separated at birth in an attempt to determine whether it was nature or nurture that determined their personalities. However unethical, the study demonstrated that a great deal of who we are comes from our genes; many of the twins bore uncanny similarities in personality and preferences despite spending decades apart.

13. The incidence of twin types and genders are oddly symmetrical. These facts about twinning are sure to leave you in awe. One third of all twins born are identical, one third are same sex fraternal and one third are male/female fraternal. Of the identical twins, half are male/male and half are female/female. Of the same sex fraternal, half are male/male and half are female/female.

A case of mistaken identity

I often tell people that, these days, I find it hard to believe Matthew and Jonathan are identical. I know we have the DNA tests to prove it, but I look at them and I see so very many differences that I wonder how anyone could mix them up at all.
Then comes a day like today.
The boys were playing with trains and cars. Matthew had been racing with Lightning McQueen in a toy garage for at least half an hour while Jonathan had been more interested in the trains. The boys decided they needed tracks of both kinds, so we dumped a few bins and started to build.
One twin focused on creating a large and winding train track while the other worked on city streets.
Then they picked up vehicles and started to play.
In less than a minute, a full-fledged brawl had broken out.
Jonathan kept trying to take Lightning from Matthew, who had been building the city. I tried offering him one of the five other Lightning McQueens they own (Yes, they are obsessed!), but he refused, insisting that particular car was his and fighting to get it back.
So I disciplined Jonathan with a time out.
Or so I thought.
Jonathan's wail as he sat in that chair was one of absolute despair.
That was odd.
Jonathan usually rages with anger in the time-out chair.
I looked more closely and saw the tiny red spider vein by the right eye.
It was Matthew.
No wonder he had expressed such despair: it really was his car.
The other twin should have been in the time-out chair.
I pulled Matthew up into my arms, held him tight and apologized over and over and over again.
I carried him to where Jonathan was playing and offered him another Lightning car in exchange. Jonathan readily agreed and the two brothers played together on the city streets that Jonathan, not Matthew, had built.
It seems Matthew has forgiven me.
I hope he has more of that forgiveness within him and that Jonathan has a wealth of it too because I am beginning to realize that I will need it. I will need lots of it and so will the many other people in their lives. And I promise that I will never doubt their zygosity again.
They are, indeed, identical twins.

So what do we call them now?

Apparently those folks who insist that Matthew and Jonathan are not identical might just be right.
Maybe not now.
But they might be right someday.
Scientists have known for years that identical twins can differ in their expression of genes due to environmental influences, such as diet. But it was always assumed that the basic DNA--the genetic framework--was precisely the same.
A recent study of 19 sets of adult identical twins has throw them for a loop.
The study, conducted by geneticist Carl Bruder of the University of Alabama, found slight differences in DNA sequences in some sets. In one set of identicals in Bruder's study, a genetic variation indicated the risk of leukemia in one twin. That particular twin did, indeed, suffer from the disease.
You see, all of us are supposed to inherit a copy of each gene from each parent, but sometimes, something happens that causes us to have too many or too few. Scientists believe those variations might put us at risk for certain diseases such as AIDS, leukemia, autism or lupus. These differences are called copy number variations and they were just discovered a few years ago.
Previously, the assumption was that if any of these variations were found in one identical twin, they would be found in the other because the twins come from the same egg and share exactly the same DNA.
This study throws that theory out the window.
What remains a mystery, however, is whether these variations occur in utero or as we age. Bruder suspects they come with age. Regardless, his findings mean studies of identical twins could be valuable in figuring out which genes are linked with certain diseases.
But the study raises an even more pressing question: if identicals are not truly identical, what do we call them now? Almost identical? Mostly identical? Sort of identical? Same-egg children?
Will I someday have to admit that those annoying people who stop me in the mall for the sole purpose of informing me that my twins are not identical simply because one has less fat in his cheeks are right?
The implications are frightening.