Embryo Screening

This is taken from a discussion I took part in concerning preimplantation genetic diagnosis, a very touchy subject from an ethical point of view, and also from a technical point of view:

“…. There have been many issues with genetic testing of the embryos for hereditary diseases such as Huntington Disease for many reasons. First, of course, during pregnancy women can have a genetic test performed on the fetus in order to find out if their infants will be affected by a known disease or not. However, many centers refuse to perform this test as it divulges information about the parents as well and usually leads to pregnancy termination. The test in itself cannot predict the time of onset of course. However, more interestingly in my opinion, this opens the door to a whole new approach to birth, in vitro fertilization with pre-implantation genetic diagnosis (PGD). This procedure is also known as embryo screening and it allows couples at risk of transmitting a genetic disease to ensure their descendants to be unaffected by the genetic disorder through artificially combining many sperm cells from a man with many egg cells from a woman to create many embryos. Then, cell samples are taken from all of the embryos and the DNA analyzed for the defective genes. The non-disease carrier embryos are selected and artificially implanted into the mother’s uterus. This allows the parent to ensure a “disease free” child and avoid having to go through the painful termination process, in case the pre-natal test is positive (see below link to video for Comprehensive Chromosome Screening technic, a novel approach to embryo screening). This method, while very appealing, is an ethical nightmare, as it opens the door to the quest for a “perfect baby” …”




  • Embryo Screening and the Ethics of Human Genetic Engineering, By: Leslie A. Pray, Ph.D. © 2008 Nature Education
  • [Ethics and medical genetics], Lacombe D., J Int Bioethique. 2012 Jun;23(2):95-102, 178-9. French.
  • Preimplantation genetic screening: “established” and ready for prime time?, Gleicher N, Weghofer A, Barad D.,Fertil Steril. 2008 Apr;89(4):780-8. Epub 2008 Mar 18. Review.

Shaman and Chief Yulik

The overcrowded city of London had been Yulik’s home for the past three years now, and still, he never missed his natal village in the vast open Siberian tundra. He was the son of Yarev Mechlanev, Shaman and Chief of the Ha’oash tribe, in the Krasnoyarsk Krai district of Russia. He was predestined to follow in his father’s footsteps and become the representative of the spirit that had been guiding his people for as long as they could remember, and yet, here he was, alone, in a sea of concrete surrounded by strangers who had never experienced the cold air brushing against their faces while their hearts pounded in their chests from the rush of a hunt. Yulik had been taught the shamanistic ways since his youth by his father as it had been done by his ancestors over the centuries while forced to receive a more appropriate education by the local government. One that fitted the times we lived in.

Yulik had battled his first evil djinn when he was nineteen years old armed with a sword and shield crafted in the most traditional shamanistic ways giving them the particularity of following their bearer into the spiritual realm, a feat only accessible to confirmed shamans. An old woman had been possessed by an evil entity and was unable to find rest with thoughts of murders invading her mind, barely able to resist them. Yulik, in a ritual dated to the New Stone Age more than 10,000 years ago, entered the spiritual realm armed and vanquished, or simply repulsed, the demon in the woman in an incredible show of force and valor. It was then that he felt the presence of his tribe’s guiding spirit in him and truly understood its might forever changing his understanding of the world. Yulik had been embraced into a higher level of being by an inexplicable force that had accepted his people as its own and him as its voice. Yarev, filled with pride, knew at that moment his tribe had found his successor and their guide in his son to lead them into the new century.

Unfortunately, Yarev’s joy was short lived. The young shaman quickly grew tired of his spiritual battles and slowly lost faith in their utilities. Modern men and medicine invaded his area with out of reach knowledge and powers. To add to it all, as if mocking him, they could cure the deadliest of ills with a simple pill and appease even the most violent of evil spirits, or so it seemed. Yulik’s enthusiasm for the old ways turned into obligation and his heart, once filled with awe, was now full of shame. His father, guided by his tribe’s spirit and sensing his son’s turmoil, sent Yulik to study environmental science in a nearby modern college under the supervision of an English professor researching the area for specific Siberian plants with potent medicinal properties.

Seven years passed since Yulik’s graduation and he was now working as a researcher under the same English professor who had taken him under his wings. He still sporadically carried his duties as Shaman of the Ha’oash tribe, but more in a ceremonial way than anything else. His father’s teachings, once bringer of truths, were now primitive wisdoms of a distant past, of a memory, of a dream. Yulik devoted almost all of his time to modern science and was very gifted at it. So gifted in fact, that he was offered a full time position in London, a position he accepted. Yulik, with a heavy heart, announced the news of his departure to his father, You can run as far as you want my son, you will never be able to escape your destiny, was all that Yarev said before bidding his son farewell.


Martin woke up with cold sweats on that day, he had the most unpleasant dream of his life in his luxurious flat on Adam street, in London. He felt his body being completely paralyzed while he was awake. He yelled and struggled but to no use, his eyes and mouth were shut and wouldn’t move. His body would not respond to any of his commands and his calls for help remained unanswered. The most terrifying part of it however was when he felt an incredible pressure being exerted on his chest, as if tiny hands were pushing him downwards suffocating him. He felt helpless and vulnerable and as if about to die so sparse his breathing had become. The experience lasted for what seemed to be hours until it suddenly stopped. He quickly got up breathing rapidly, passed his hands over his body and checked every single one of his limbs. Once satisfied with his scrutiny, he went to the kitchen and made himself a cup of coffee. He thought about the incident for a good half an hour and blamed it on something he ate the previous night before preparing himself for work. However, the incident repeated itself every night over the next three days leaving Martin no choice but to see a shrink one of his friends had recommended. His doctor explained to him that he was the victim of sleep paralysis and of its side effects. It was a common state experienced at least once by most of the population. It was a rare event for it to occur four times in a row but was not unheard of. The main cause was probably a change in his stress levels as a consequence of his grandmother’s poor health and of the prolonged absence of his wife and kid who had to stay by her side. In addition, his inability to visit her himself because of work aggravated his mental pressure. Martin was pleased and convinced by the diagnosis of his doctor and agreed to take a benzodiazepine derivative drug that would help him relax before he went to bed. He was to swallow a pill of Valium every night till he felt better.


“Why do you want to kill this one?”

“Because I feel like it!”


“Because I fell like it!”

“You know what happens when we are so obvious in our deeds, don’t you?”

“Shut the fuck up! They won’t do shit to me!”

“What? What makes you so special?”

“I have his protection…”

“What the… Impossible! You… a lowly spirit roaming the Earth have his protection?”

“Screw you! After this, I am going up the ladder bitch!”

“Yea… right… like this ever gonna happen… I am getting as far away from you as possible…”

“Yea run… that is all you do and will ever do!”


Yulik was having his morning coffee at his favorite shop on this beautiful spring day. How much he loved the paved city with its tall stone structures. He even enjoyed the fumes that the many cars coughed up. It reminded him of where he was and each time it brought a smile on his face. The memories of his nights spent in the freezing winds of the Siberian plains were long gone, forever behind him. He still sensed the spirits all around him but barely paid them any attention, just tricks of the mind. He hadn’t practiced any of his shamanic teachings for over three years now, he didn’t need to anymore. He was able to function like any other man, without the help of a benevolent spirit. He was forging his own destiny based on rational thoughts and decisions, and he was good at it. Nonetheless, Yulik was not his usual radiant self on that day. Prophetic dreams had been invading his mind for the past weeks. They kept telling him that something bad was to happen, that he was to stop it by any means necessary. He didn’t believe in them anymore and yet he was unable to make them stop, no matter how hard he tried. His shamanic years were behind him, yes, but these visions could not be denied. Yulik knew he had to answer them. He was to hear the call of the spirit of his tribe once again.


Martin slept the next couple of nights without incident to his relief, or so he believed. He praised his doctor every morning and the benefits of modern medicine, and more particularly, that of Valium. His wife and son were to arrive the next day, and he was glad at the news. He missed them dearly.


“Enjoy your rest you bastard, tonight you die!”


A powerful dream woke up Yulik in the middle of the night. He saw an evil spirit of the Earth claim the life of an innocent for no other reason than its pleasure. He quickly got up from his bed, in his little studio on Cromwell road, showered and undusted both his shield and sword. He never thought he would have to ever use them again, especially not in London. He had only taken them at the explicit request of his father, so that he always remembered who he was and where he came from. He placed them in a bag and grabbed a cab. He didn’t know where to go, but, helped by his spirit, he was able to direct the driver. They reached Adam street in less than twenty minutes.


Martin woke up to find himself once again completely paralyzed unable to even open his eyes. He at first smiled, convinced that since now he knew what was happening he could control it and, maybe, turn the experience into something pleasant. He felt tiny fists pushing him downwards making his breathing difficult. He quickly calmed his fears in order to regain some control of his body and forced himself to think happy thoughts. To his dismay the tiny fists grew in size and in strength. Martin was barely able to breathe. He tried to yell, to wake up, but to no avail. Panic overtook him then hysteria when he clearly heard a voice say ”Die you bastard!” Martin’s heart was ready to give up under the stress when the pressure suddenly stopped never to return. He woke up, got himself a glass of water and ingurgitated another pill before going back to bed.


When Martin was fighting for his life, Yulik was on the sidewalk, on Adam street, in front of the building, chanting and dancing to enter the spiritual realm. Once the deed done, he banged his sword on his shield in the shamanistic traditional way forcing the evil spirit to answer his call, if there was one. The demon had no choice. It stopped tormenting Martin and went to face Yulik. The djinn laughed at the sight overly confident in its innate abilities. The shaman, inhabited by his tribe’s spirit, with a single strike of his sword, sent it back from where it came from. Just a lowly one, was all that Yulik could think before going to a nearby coffee shop for a well earned sandwich. He stayed at the Coffee Republic until 11AM not understanding why he had been called after so many years for such a trivial task. He even believed for a moment that he was going mad, that he had imagined it all. It was not until he saw a taxi arrive that he realized how important his actions had been. A woman accompanied by her young son, he was no more than 6 years old, were unloading their luggage. They were welcomed by Martin whom Yulik recognized from his visions. Terror could still be seen on his face. Yulik smiled and decided at that moment to return to his natal tundra to fulfill his destiny as Shaman and Chief of his tribe and lead his people into the new century, his true and only calling.


When Yulik’s eyes met with the boy’s, he immediately recognized him for what he was, a child of light. They saluted themselves as kindred spirits would before parting each their own way with renewed faith in their hearts.


RNA interference

Cells have many ways of regulating gene expression, and one of the most efficient of them would be RNA interference (RNAi). This method allows the cell to effectively silence, or repress, expression of genes by using different types of short RNAs that binds to homologous sequences in order to inhibit translation, to degrade or/and, sometimes, to silence the promoter of the target gene mRNA. This method is so effective that it is now widely used in laboratories for in vivo experiments and, thus, I thought I should say a few words about it before introducing the video made by Nature about this technique:


Cells of multi-cellular organisms not only require oxygen and nutrients to survive, they also need survival signals called trophic factors. In the absence of such signals, signaling pathways that prevent the cell to undergo a “suicide” program are not activated and, thus, result in cell death.

Analysis of the development of the nervous system demonstrated the essentiality of trophic factors in cellular development. Indeed, it was shown that more cells grew than actually survived when neurons developed to connect to other neurons (or muscles), even over long distances. It was further demonstrated that only those cells that succeeded in making connections survived while the others died.

An example of such trophic factors was discovered through the study of innervation of developing limbs in chick embryos and was simply known as nerve growth factor (NGF). It was then identified to belong to the neurotrophins, which binds to and activate a family of receptor tyrosine kinases called Trk. NGF binds with high affinity to TrkA and, through this binding, provides the necessary surviving signal to avoid “suicide” for different classes of neurons that successfully made connections. Indeed, only Trk receptors produced on the growth cones of the extending axons of neurons trying to make connections bind neurotrophins produced by target tissues.

This process is key during developmental processes as it ensures that the right neurons survive and in the required amount for proper target innervation. Furthermore, neurotrophins allow for cell fate decision, axon growth, dendrite pruning, the patterning of innervation and the expression of proteins crucial for normal neuronal function, such as neurotransmitters and ion channels. Neurotrophins were also found to regulate many aspects of neural function, e.g. in the mature nervous system, they were demonstrated to control synaptic function and synaptic plasticity, while continuing to modulate neuronal survival.




  • Lodish et al., Molecular Cell Biology, Sixth Edition, 2008, pp. 936-938
  • Neurotrophins: roles in neuronal development and function, Huang EJ, Reichardt LF., Annu Rev Neurosci. 2001;24:677-736. Review.

Moment of Clarity

It was the first Monday of the month of November, and Kenro was having a bad day at the downtown Vancouver trading company where he worked.  His results had been sliding downwards for the last twelve weeks. Given the present state of the market, though, it wasn’t his fault: everybody was losing money, and the new regulations that kept popping out of Washington didn’t help. Of course he wanted to build a better future—who didn’t?—but he still had a mortgage to pay and a family to feed.

Kenro was the proud father of two beautiful daughters and husband to his beloved Christine. They lived in a beautiful apartment in False Creek with no worries in the world…until three months ago, that is. It had all started with a bad gamble on the expected quarterly earnings of a Canadian telecommunications company. The company had made headlines when they had claimed to have developed the next generation of communication technology. That claim turned out to be unfounded. Instead of earning money, the company was forced to return to the drawing boards, plunging its stocks from a high of $18 to a dreadful low of $2 a share.

Kenro’s clients lost a lot of money, and the trading company he was working for decided to put him on review. Kenro had been working twelve hours a day ever since then, desperately trying to make up for his losses. He didn’t have any luck, though—each new investment he made turned out to be a worse performer than the previous one. His review was in less than a week, and unless he could come up with a golden stock, he was sure to lose his job, his reputation. Even worse, he could lose the life he had spent the last ten years building with his family. Yes, Kenro was having a really bad day on that first Monday of the month of November.

Tuesday: -5 until D-Day

Kenro was frantically working the phones and computers, looking desperately for leads on any stocks that could buy him a little more time before he was fired. (Which he was sure was coming.) He called everyone he’d ever met, everyone he’d ever laid his eyes on, even random people from the yellow pages who seemed like they might aid him in his search. He prayed to all the gods he knew of and all the demons he’d ever heard of. He’d never been a man of faith—he considered it a weakness of the human spirit to find comfort where there was none—but for the past few days, he’d been praying more than a Muslim making his pilgrimage to Mecca.

Kenro was desperate and flat out of ideas. The vision of losing everything he had worked for so long became bigger and bigger in his mind; with that vision came the sense of unavoidable fatality. Kenro had little hope left and knew that he was but a step away from what he understood would be eternal damnation. The more he pondered his terrible situation, the sicker and weaker he got. Images of his family living on the streets flashed through his thoughts, images of his daughters crying in hunger and trembling in fear.  He sank into a deep despair, his soul plunged into a bottomless abyss that offered no possible return. Light had gone forever from his heart, to be replaced by inescapable doom.

Wednesday: -4 until D-Day

Kenro arrived at the office at 8 a.m. knowing that Wednesday was going to be his last day if he didn’t find a profitable stock. He had spent most of the previous night thinking about alternate solutions to his awful situation and had only been able to come up with one option: he would orchestrate his own death so that his family could collect the insurance money.  Then they would never have to experience the harshness of a penniless life.

It was a simple act, really—all he had to do was drive his car off the side of a nearby ravine while making sure to leave evidence on the road that would point to a mechanical failure in the vehicle. The insurance company would be forced to pay out the million-dollar policy he’d been paying into the past five years. That money—along with his family’s other assets—would be more than sufficient to pay off his debts and give his beloved family plenty of time to grieve and move on. He was sure that they would be better off without him, away from his failures and incapacity to provide them with the life they deserved…the life he’d been promising Christine ever since he’d met her.

His decision was final. If he couldn’t find a profitable stock, he would accidentally kill himself the next morning as he drove his usual route to the opposite shore of Vancouver. That decision made, he sat comfortably on his chair in front of his computer and got back to work, searching for the elusive stock that would save him from the desolated world he found himself in.

Kenro worked nonstop for twelve hours, looking for anything that would allow him to escape his impending death…but his efforts yielded nothing. He turned off his computer at 10 p.m., knowing that his life was coming to an end. He decided that he wasn’t going to go straight home to spend time with his family the way he usually did—he simply couldn’t face them. Instead, he would go have a drink or two in a nearby pub and smoke a few cigarettes. He had stopped smoking more than five years ago, but tonight that didn’t matter. He was going to have the condemned man’s last cigarette and he was going to enjoy it.

He entered Smiley’s pub unnoticed by anyone and went straight to the counter. He ordered a Guinness and slowly savored it, enjoying every sip of and making it last for hours. He looked at all the people around him and reminisced about the most enjoyable moments of his life. Most of them involved his wife Christine and their two daughters, Kim and Lilly. Each time he thought about the sadness his death would bring them, he took another sip of his beer and forced himself to remember the million-dollar insurance policy.

He’d been at the counter for almost an hour before a man of medium build who looked to be in his mid-thirties walked up to the bar and sat down next to Kenro. The man was just over six feet tall and had a receding hairline. His wide shoulders towered over a belly that was testament to his fondness for food; his smile could’ve charmed snakes.
He nodded his head in Kenro’s direction and then ordered a Guinness. Kenro paid the man no heed—he had no time to waste on silly pub conversations. He shifted to his left, putting his back towards the man as he took another sip of his beer.

The man just smiled and put his own glass to his lips. He gulped his stout, put his glass back on the counter, and tapped Kenro’s shoulder.

“Hey, my friend, you look like you need the company of an angel!”

Kenro turned, startled by the man’s words. He had never heard anyone speak of angels, but what shocked him even more was that when he meant to respond in a way that would brush the man off, he was caught and held by the intensity of the other’s gaze. The man wasn’t threatening; he just exuded an intense charisma that left Kenro speechless.

Kenro remained staring and mute, incapable of uttering a single word or moving a finger.

“What? You need more time to think that being left alone right now is not the best thing for you?” the man said jovially.

“Uh…I…I am Kenro… Nice to meet you… You are?” Kenro found himself saying.

“I am Rehael,” the man answered, and reached out to shake Kenro’s hand. “So…what troubles you so much?”

Kenro was once more dumbfounded by the intensity of the man’s words and gestures. He found himself unable to hide any of his emotions. Even more important, he found himself unable to lie. Once he’d spilled his guts to the stranger—omitting the part about the orchestrated suicide—he held himself stiffly, staring at Rehael with a blank look.
Rehael looked at Kenro and began laughing. “I can’t believe this small affair is the source of so much misery for you!”

Kenro was insulted by the comment and tried to turn his back on the man again. Before he could do so, however, he was halted by Rehael’s hand on his right shoulder.

“Don’t take offense, my friend. I was never known for my tact. Actually, I am more famous for my brutality than anything else!” he explained before laughing again. This time, Kenro did not feel insulted—he actually felt relieved by the friendly fellow’s self-derision.

“It’s your lucky day, Kenro,” the man continued. “Transfer everything you have into Siman’s American stocks. Your financial troubles will be forever behind you, I assure you…”

Kenro, feeling the man was making fun of him again, flagged down the bartender for his bill.

“Come now, Kenro—what do you have to lose? What is one more day?” Rehael said with true compassion in his voice.

Kenro stopped counting out his money and looked at the man, finally feeling warmth return to his heart.

“Invest in the morning—you will have a good surprise before the end of the day! What is another day?” Rehael insisted again before taking his leave.

Kenro paid his bill and went home. I can deal with one more day, was his last thought before entering a deep slumber.

Thursday: -3 until D-Day

To the surprise of his colleagues, Kenro was at the office by 8 a.m. the next day even though it was the anniversary of his father’s passing. He had never before missed honoring the tomb of his father first thing in the morning on that morning every year, yet he was in front of his computer instead of in the graveyard.

As soon as the markets opened, he invested all his capital in Siman. As Rahael had said, he had nothing to lose anymore. He spent the next five hours drinking coffee and fidgeting in his chair.

At 2:01 p.m., Siman’s stocks began to go up. The CEO of the company had made an announcement that shocked everyone: the company had been working secretly on a merger with Google for the past three months, and the deal had been confirmed just a few hours earlier. In less than two hours, Siman’s shares went from $18 a share to $67.

Kenro had reversed all of his losses and even made money in a single shot. His career was saved, his reputation was saved, his life was saved. He thanked whatever gods he knew of for having sent Rehael onto his path.

Friday: D-Day Infinity

Kenro left the office at 5 p.m. His boss had come by that morning to congratulate him on having been able to make up for his past mistakes and to praise him on his incredible sense for capturing exceptional opportunities. His job was no longer in jeopardy; his life was officially saved.

Kenro went straight to Smiley’s pub in the hopes of seeing Rehael once more. He entered the establishment and saw the good man sitting alone at a table in the back.

He ran to him. “Rehael!” he exclaimed.

Rehael looked at him and smiled. “Kenro! I guess you heard the good news, didn’t you?” he said with a wink.

“How did you know? Who are you?”

Rehael laughed. “An angel, of course!”

Kenro looked at him, perplexed. It must be another of Rehael’s jokes, he told himself. “No, seriously…”

“I’m an Angel of God! You know what angels are, don’t you?” Rehael replied in a voice of complete sincerity.


“An angel of God. You know, Adam and Eve…Abraham…you must know about Jesus!”

Kenro was incapable of saying anything.

“Let me guess—you need proof!” Rehael said, then laughed out loud.


Rehael just looked at Kenro, enveloping him in an aura of undeniable mercy.

Kenro lowered his head and pleaded for forgiveness. “I shall be forever in your debt and forever adore you!” he said to Rehael, his heart full to bursting.

The angel looked at him, clearly displeased, and said, “Adore me? No, you have mistaken for someone else. Be grateful for the Creator and use what He has given you in His way. That is all that He truly asks of you, you know.”

Kenro’s eyes welled with gratitude. “I will do so forever!”

Rehael smiled. “You can go now. Return to your family and lead your life as it ought to be.”

Kenro nodded and left to be in his family’s company, his heart filled with joy and strength. He finally knew what faith was; for the first time in his life, he felt complete.

Saturday: D-Day -298

Kenro woke up the next day with a strange feeling in his heart. He got up from his bed and went to make himself some coffee. As he was waiting for the coffee machine to finish its routine, images of his encounter with Rehael invaded his mind. He kept thinking about everything that he had said and done and could not help himself from smiling at the sneakiness of the self-proclaimed angel.

Obviously, Rehael—if that was even his real name—had given him an insider tip to cover his own illegal investments. Kenro would have reported the man on the spot if the tip hadn’t saved his career and his life. Rehael—or the organization he was working for—must have been watching for potential candidates who would be desperate enough to play their game.

That was the only logical explanation, and the only one that made any sense at all. Kenro poured himself a cup of coffee and went about his usual day, enjoying his newfound success and forgetting all that rubbish about gods and angels.