gene-mutations

repeat after me:

it’s okay to be human!!!! uwu

bigots are the problem, homo sapiens are not.

it’s not okay to hate people for not being mutants.

it’s not okay to kill all of the humans.

hating or killing an innocent person solely because of their lack of a mutated x-gene makes you an asshole, erik.

reblog if you’re for mutant equality, NOT mutant supremacy!!!!!!!! uwu uwu uwu

False-colored scanning electron micrograph of human embryonic stem cell (gold) growing within a cradling cluster of supporting fibroblasts. Image courtesy of Annie Cavanaugh, Wellcome Images

The trouble within stem cells

Inducing human pluripotent stem cells to become any kind of desired cell has the potential to transform medicine: Doctors could, for example, repair, rebuild – maybe even build anew – damaged or diseased organs.

Of course, nature has had millions of years to master the process – and it doesn’t often even attempt things like regeneration. Humans are strictly rank beginners, still struggling to fully understand the countless complexities of biological construction and overcome the myriad obstacles to success.

Chief among them is the concern that induced stem cells might carry or create mutations that, in the process of differentiation and growth, would introduce or exacerbate disease, rather than cure it. A 2011 paper published in Nature by Kun Zhang, PhD, at UC San Diego, for example, found that genetic material of reprogrammed cells may in fact be compromised.

Nowhere is this more worrisome than in efforts to find stem cell-based therapies to treat cancer, which is essentially a disease of gene mutations. The greater the “mutational load,” the greater the chance of cancer.

In a new paper, published in the journal Cell Reports, Louise Laurant, MD, PhD, adjunct assistant professor in the Department of Reproductive Medicine at UC San Diego School of Medicine, and colleagues describe analyses of two sets of human embryonic stem cell (hESC) lines.

They showed for the first time that different genetic aberrations tend to occur at different stages of development in hESCs. During preimplantation embryo development and early derivation, mutations are mainly deletions or “loss of heterozygosity,” which occurs when some copies of primary nucleobases (cytosine, guanine, adenine, thymine and uracil) are missing.

Conversely, long-term culturing of hESCs aberrations are more frequently duplications of genetic information.

The findings reinforce the importance and need to measure and monitor the genetic integrity of hESCs, and specifically point to areas of concern.

Serious efforts are being made in this regard. For example, Steven Dowdy, PhD, professor in the UC San Diego Department of Cellular & Molecular Medicine, recently published a paper describing a simple, easy RNA-based method of generating human induced pluripotent stem cells. You can read the news release here.

@chat-noir-knight

[Gabriel remembered the day he realized Adrien would be different. He was doing fine for the first six months, growing and hitting each of his milestones. But after he learned to crawl, he never reached another one.
And he never would. Adrien was born with a neurological disorder caused by a rare gene mutation. He would never learn to walk or properly speak or read. He acted like a feral child and by law he was treated like one. And now that Gabriel’s wife was gone, Gabriel had to care for his ill son on his own]

How do mutations in genes result in red-green color blindness? Approximately 8% of males are red-green colorblind, and while the condition can be inconvenient, it is not life-threatening and most learn to adjust at an early age.

Image: Example of an Ishihara color test plate. Creator unknown. Public domain via Wikimedia Commons.

Link seen between seizures and migraines in the brain

Seizures and migraines have always been considered separate physiological events in the brain, but now a team of engineers and neuroscientists looking at the brain from a physics viewpoint discovered a link between these and related phenomena.

Scientists believed these two brain events were separate phenomena because they outwardly affect people very differently. Seizures are marked by electrical hyperactivity, but migraine auras – based on an underlying process called spreading depression – are marked by a silencing of electrical activity in part of the brain. Also, seizures spread rapidly, while migraines propagate slowly.

“We wanted to make a more realistic model of what underlies migraines, which we were working on controlling,” said Steven J. Schiff, Brush Chair Professor of Engineering and director of the Penn State Center for Neural Engineering. “We realized that no one had ever kept proper track of the neuronal energy being used and all of the ions, the charged atoms, going into and out of brain cells.”

Potassium and sodium contribute the ions that control electricity in the brain. The Penn State researchers added fundamental physics principles of conservation of energy, charge and mass to an older theory of this electricity. They kept track of the energy required to run a nerve cell, and kept count of the ions passing into and out of the cells.

The brain needs a constant supply of oxygen to keep everything running because it has to keep pumping the ions back across cell membranes after each electrical spike. The energy supply is directly linked to oxygen concentrations around the cell and the energy required to restore the ions to their proper places is much greater after seizures or migraines.

“We know that some people get both seizures and migraines,” said Schiff. “Certainly, the same brain cells produce these different events and we now have increasing numbers of examples of where single gene mutations can produce the presence of both seizure and migraines in the same patients and families. So, in retrospect, the link was obvious – but we did not understand it.”

The researchers, who also included Yina Wei, recent Penn State Ph.D. in engineering science and mechanics, currently a postdoctoral fellow at University of California-Riverside, and Ghanim Ullah, former Penn State postdoctoral fellow, now a professor of physics at University of South Florida, explored extending older models of brain cell activity with basic conservation principles. They were motivated by previous Penn State experiments that showed the very sensitive link between oxygen concentration with reliable and rapid changes in nerve cell behavior.

What they found was completely unexpected. Adding basic conservation principles to the older models immediately demonstrated that spikes, seizures and spreading depression were all part of a spectrum of nerve cell behavior. It appeared that decades of observations of different phenomena in the brain could share a common underlying link.

“We have found within a single model of the biophysics of neuronal membranes that we can account for a broad range of experimental observations, from spikes to seizures and spreading depression,” the researchers report in a recent issue of the Journal of Neuroscience. “We are particularly struck by the apparent unification possible between the dynamics of seizures and spreading depression.”

While the initial intent was to better model the biophysics of the brain, the connection and unification of seizures and spreading depression was an emergent property of that model, according to Schiff.

“No one, neither us nor our colleagues anticipated such a finding or we would have done this years ago,” said Schiff. “But we immediately recognized what the results were showing and we worked intensively to test the integrity of this result in many ways and we found out how robust it was. Although the mathematics are complex, the linking of these phenomena seems rock solid.”

The ability to better understand the difference between normal and pathological activity within the brain may lead to the ability to predict when a seizure might occur.

“We are not only interested in controlling seizures or migraines after they begin, but we are keen to seek ways to stabilize the brain in normal operating regimes and prevent such phenomena from occurring in the first place,” said Schiff. “This type of unification framework demonstrates that we can now begin to have a much more fundamental understanding of how normal and pathological brain activities relate to each other. We and our colleagues have a lot on our plate to start exploring over the coming years as we build on this finding.”

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Two blue chicks

The image above shows the skeleton of a normal chick (top left) and a chicken with a severe mutation (top right). 

The mutation is in a gene called TALPID3 which is important for development. Chickens which have lost the function of TALPID3 have brain deformities, small lungs, liver fibrosis and extra fingers.

Scientists at the Roslin Institute have now found that humans with a rare genetic disorder that affects brain development, called Joubert syndrome, also have mutations in TALPID3. 

By investigating the impact of the gene at the cellular level in chickens, the researchers have provided further insight into the specifics of Joubert syndrome in people.

Read more 

FACT #81:

Is everyone who has blue eyes related?

Originally posted by sonianicky

If you have blue eyes, you may be related to every other blue-eyed person in the world. Researchers in Denmark have found that every person with blue eyes descends from just one “founder,” an ancestor whose genes mutated 6,000 to 10,000 years ago. Before then, everyone had brown eyes.

(src)

Interested in the Human Genome?

A few years ago, the US Department of Energy’s Genomic Science Program produced a poster highlighting the loci (gene location) of hundreds of genetic conditions.

Unfortunately they had a very small supply, and this was quite a few years ago, so it has long since been out of stock. However, their website for the poster is still up, and they offer a high quality PDF file of the poster for download. I highly recommend checking it out.

They also have individual image files of each chromosome for easier legibility, which look something like this:

I only remembered this porter tonight when replying to a post about another science poster, but it occurred to me that the science side of tumblr might find it as neat as I do.


Source/credit: U.S. Department of Energy Genomic Science program’s  Biological and Environmental Research Information System (BERIS). Their website states that permission to use these images is not needed however credit is requested.  Website: http://genomicscience.energy.gov.


(Image caption: Alterations of the human 16p11.2 chromosomal region lead to a variety of cognitive disorders, including autism. Credit: Pasieka/Science Source)

New findings reveal genetic brain disorders converge at the synapse

Several genetic disorders cause intellectual disability and autism. Historically, these genetic brain diseases were viewed as untreatable. However, in recent years neuroscientists have shown in animal models that it is possible to reverse the debilitating effects of these gene mutations. But the question remained whether different gene mutations disrupt common physiological processes. If this were the case, a treatment developed for one genetic cause of autism and intellectual disability might be useful for many others.

In a paper published today in the online edition of Nature Neuroscience, a research team led by Mark Bear, the Picower Professor of Neuroscience in MIT’s Picower Institute for Learning and Memory, showed that two very different genetic causes of autism and intellectual disability disrupt protein synthesis at synapses, and that a treatment developed for one disease produced a cognitive benefit in the other. The research was performed by postdoc and lead author Di Tian, graduate student Laura Stoppel, and research scientist Arnold Heynen, in collaboration with scientists at Cold Spring Harbor Laboratory and Roche Pharmaceuticals.

Researching the role of fragile X syndrome

One heritable cause of intellectual disability and autism is fragile X syndrome, which arises when a single gene on the X chromosome, called FMR1, is turned off during brain development. Fragile X is rare, affecting one in about 4,000 individuals. In previous studies using mouse models of fragile X, Bear and others discovered that the loss of this gene results in exaggerated protein synthesis at synapses, the specialized sites of communication between neurons.

Of particular interest, they found that this protein synthesis was stimulated by the neurotransmitter glutamate, downstream of a glutamate receptor called mGluR5. This insight led to the idea, called the mGluR theory, that too much protein synthesis downstream of mGluR5 activation gives rise to many of the psychiatric and neurological symptoms of fragile X. Bear’s lab tested this idea in mice, and found that inhibiting mGluR5 restored balanced protein synthesis and reversed many defects in the animal models.

Different genes, same consequences

Another cause of autism and intellectual disability is the loss of a series of genes on human chromosome 16, called a 16p11.2 microdeletion. Some of the 27 affected genes play a role in protein synthesis regulation, leading Bear and colleagues to wonder if 16p11.2 microdeletion syndrome and fragile X syndrome affect synapses in the same way. To address this question, the researchers used a mouse model of 16p11.2 microdeletion, created by Alea Mills at Cold Spring Harbor Laboratory. 

Using electrophysiological, biochemical, and behavioral analyses, the MIT team compared this 16p11.2 mouse with what they already had established in the fragile X mouse. Synaptic protein synthesis was indeed disrupted in the hippocampus, a part of the brain important for memory formation. Moreover, when they tested memory in these mice, they discovered a severe deficit, similar to fragile X.

Restoring brain function after disease onset

These findings encouraged the MIT researchers to attempt to improve memory function in the 16p11.2 mice with the same approach that has worked in fragile X mice. Treatment with an mGluR5 inhibitor, provided by a team of scientists at Roche led by Lothar Lindemann, substantially improved cognition in these mice. Of particular importance, this benefit was achieved with one month of treatment that began well after birth. The implication, according to Bear, is that “some cognitive aspects of this disease, previously believed to be an intractable consequence of altered early brain development, might instead arise from ongoing alterations in synaptic signaling that can be corrected by drugs.”

Current research indicates that well over 100 distinct gene mutations can manifest as intellectual disability and autism. The current findings are heartening, as they indicate not only that drug therapies might be effective to improve cognition and behavior in affected individuals, but also that a treatment developed for one genetic cause might apply more broadly to many others.

The scary reason many people get cancer: bad luck

Despite the proven risks associated with fast food, sunburns, cigarettes and lack of physical activity, it turns out that most cancer diagnoses are actually a matter of chance. A study published in 2015 found that most cancer is caused by random gene mutations, which is terrifying. But the researchers behind the study were anxious to clarify that this doesn’t mean there’s no rhyme or reason to why people get cancer.

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anonymous asked:

The color of blood is related to the amount of oxygen bound to the red blood cells. The more oxygen in the blood, the brighter red it appears. As oxygenation of the blood gets lower the blood gets darker and darker. I think you are right about Lexa's blood. And your theories are the best!!

Exactly! Okay, so here is my theory about ‘safeguards’ created against ALIE (i thought of most of this while driving today. lol.): 

1) A person has to be willing to say ‘yes’ to go into the City of Light (however, a person can be ‘forced’ into saying ‘yes’ by ALIE threatening their loved ones – that is my theory to why Clarke is inside the City of Light)
2) Polis Tower has a machine that projects a frequency that surrounds Polis that protects it’s citizens from ALIE’s frequency. There is also an ‘access point’ into the City of Light in Polis Tower to conduct the Conclave.
3) Gene/blood mutation that makes a person’a blood appear black. This mutations prevent’s ALIE from controlling a person’s brain ‘completely’ and their body. 

My theory is that there is something in their blood that when it hits the air it turns a ‘darker’ color instead of a vibrant red. This ‘thing’ inside their blood prevents ALIE from controlling their bodies while their minds are in the City of Light. Right now, when a person is inside the City of Light, ALIE has complete control over their body and can kill them. But! People with this ‘black blood’ have a mutation that doesn’t allow ALIE to latch onto their motor neuron while their brains are in the City of Light. 

This ‘black blood’ is a safe guard against ALIE. The creators of ALIE saw that a side effect of the City of Light is that ALIE has control over someone’s body and can have them kill themselves. Imagine a scientist (in the past) was going through a trial run into the City of Light, and ALIE took control of his body and had him kill himself. Maybe that is why Rebecca has this face in the trailer:

…maybe she just witnessed her creation kill someone. So, they started to create a ‘gene mutation’ to add to the human genome to counteract this. People could go into the City of Light and ALIE wouldn’t be able to control their body while they were there, they would also have control over their mind while in the City of Light. This is also a safeguard so that in case ALIE somehow got ‘free’ and ‘enslaved’ all the humans, there would be these people that would be able to fend off ALIE’s control and shut her down. There might be a ‘lever’ or thing inside the City of Light that has to be found in order to destroy her. 

However, the gene mutation wasn’t complete before ALIE escaped. It is a recessive gene that only is activated in a few people – with varying potency. So, certain’s people’s blood would appear black, but they wouldn’t have enough of this ‘mutation’ to counteract ALIE. ALIE would still be able to control their bodies or their mind enough to override it and kill the person. So, this is the purpose of the Conclave. The Nightblood is sent into the City of Light, via a machine inside Polis tower, and they are tested to see if they have enough of this mutation to be a Commander. 

Inside Polis tower there is a machine that is able to connect a person to the City of Light via ‘hard wire’ (think about electrodes being placed on the person’s head. Actually, this facility that you see behind Rebbecca might be a room inside Polis Tower and this might be where this ‘machine/computer’ is at.) Titus might be a buyer of technology that Emori mentioned to keep the machine running. So, Titus conducts the Conclave on a Nightblood to see if their blood has enough of this mutation to fend ALIE’s control off. Now, they can still look like they are in physical pain because ALIE can still attack the pain centers of their brain – but not enough to make their body ‘give out’ or die due to pain. The Nightblood either pass the Conclave or ALIE kills them because they don’t have enough of the mutation in their blood.

I have theorized that maybe Clarke is looking at Aden in pain or dead because he is in his Conclave. Titus is wearing warpaint because the Conclave is a ceremony and Grounders wear warpaint during ceremonies. I have also previously theorized that the reason why Trikru warpaint is black, is because of this ‘black blood’ is superior idea. 

Polis Tower is a safe guard itself. The machine inside of it sends out a frequency that creates a force field around Polis and it’s inhabitants. Maybe the [!] that is marked red, is pointing out to ALIE that there is a threat inside Polis tower. This threat is this machine. ALIE needs to disable it, but she can’t control the bodies of people to disable it due to this frequency that this machine gives off that disrupts her control. She needs people to be willing and wanting to destroy Polis and this machine. So, she needs the Skaikru to attack Polis, or she needs Azgeda to take control of the tower and disable it. Azgeda or Skaikru taking control would also lead to them killing all the Nightbloods and future Commanders that could destroy her, due to their superior blood. 

I think that if a Nightblood that passes their Conclave, they become ‘soldiers’ that go into the City of Light (via this machine) and try to defeat ALIE from the inside. Commanders are nightbloods that are able to resist ALIE’S control better than most. Commanders go into the City of Light to find a way to defeat ALIE, due to them having more of the antigen. Maybe this is why Titus has been fleimkepa for 4 commanders. Maybe the Commanders before Lexa didn’t have enough of the mutation in their blood and ALIE was able to kill them after they went into the City of Light a certain amount of times. MAYBE this is the significance behind Lexa’s tattoo. Maybe she adds another band to her tattoo after she has completed a successful ‘mission’ in the City of Light. 

 Lexa is ‘special’ and as Titus said, “No one has done what you have, we are so close to our goal”. This ‘goal’ might be referring to defeating ALIE. I think that this statement isn’t referring to Lexa creating peace between the 12 Clans…we are just supposed too think that that is what Titus was referring to. But, at the end of the show we would see that he was talking about defeating ALIE instead, and we just made an assumption.

NOW!!!! Let’s think about Lexa’s line to Titus “Clarke’s special” “You’re special Heda….no one has done what you have.” Catch that? ‘no one’ Clarke: “I am no one”. There is something inside of Clarke that isn’t this mutation, but allows her to also fight ALIE’s control “No one Clarke has done what you have.” Clarke and Lexa are both ‘special’. This might be a stretch, but what if Clarke and Lexa TOGETHER are able to defeat ALIE because of their ‘real human connection’– their love. Love is not weakness; it is a strength. That would be paralleling season 2 beliefs with season 3. This (’no one’/’special’) would be AMAZING foreshadowing. And I honestly wouldn’t put it past the writers.  

Wow, okay idk if anything I just wrote made sense. So, in conclusion, their blood looks black because when their blood is exposed to the air, it doesn’t turn red. Due to this mutation it overrides the ‘natural’ reddening of the blood looks black instead. Their blood INSIDE their body is still very much a dark redish color like most humans. This is why they don’t have weird colored skin and have a normal complexion. AND you have to remember that this is a Sci-Fi show. 

The 3230 genes you can’t do without

Fiddle just a little bit with any one of about 3200 genes in the human body and you could be toast. That’s the conclusion of a new study, which finds that about 15% of our 20,000 genes are so critical to our livelihood that even minor mutations can kill us before we’re born. The findings should help researchers better track down the genes that cause human disease.

By comparing sets of genes from tens of thousands of people, researchers have found some that the body can’t seem to live without. Jane Ades/NHGRI

Dozens of Genes Associated with Autism in New Research

Two major genetic studies of autism, led in part by UC San Francisco scientists and involving more than 50 laboratories worldwide, have newly implicated dozens of genes in the disorder. The research shows that rare mutations in these genes affect communication networks in the brain and compromise fundamental biological mechanisms that govern whether, when, and how genes are activated overall.

The two new studies, published in the advance online edition of Nature (1, 2) on October 29, 2014, tied mutations in more than 100 genes to autism. Sixty of these genes met a “high-confidence” threshold indicating that there is a greater than 90 percent chance that mutations in those genes contribute to autism risk.

The majority of the mutations identified in the new studies are de novo (Latin for “afresh”) mutations, meaning they are not present in unaffected parents’ genomes but arise spontaneously in a single sperm or egg cell just prior to conception of a child.

The genes implicated in the new studies fall into three broad classes: they are involved in the formation and function of synapses, which are sites of nerve-cell communication in the brain; they regulate, via a process called transcription, how the instructions in other genes are relayed to the protein-making machinery in cells; and they affect how DNA is wound up and packed into cells in a structure known as chromatin. Because modifications of chromatin structure are known to lead to changes in how genes are expressed, mutations that alter chromatin, like those that affect transcription, would be expected to affect the activity of many genes.

One of the new Nature studies made use of data from the Simons Simplex Collection (SSC), a permanent repository of DNA samples from nearly 3,000 families created by the Simons Foundation Autism Research Initiative. Each SSC family has one child affected with autism, parents unaffected by the disorder and, in a large proportion, unaffected siblings. The second study was conducted under the auspices of the Autism Sequencing Consortium (ASC), an initiative supported by the National Institute of Mental Health that allows scientists from around the world to collaborate on large genomic studies that couldn’t be done by individual labs.

“Before these studies, only 11 autism genes had been identified with high confidence, and we have now more than quadrupled that number,” said Stephan Sanders, PhD, assistant professor of psychiatry at UCSF, co-first author on the SSC study, and co-author on the ASC study. Based on recent trends, Sanders estimates that gene discovery will continue at a quickening pace, with as many as 1,000 genes ultimately associated with autism risk.

“There has been a lot of concern that 1,000 genes means 1,000 different treatments, but I think the news is much brighter than that,” said Matthew W. State, MD, PhD, chair and Oberndorf Family Distinguished Professor in Psychiatry at UCSF. State was co-leader of the Nature study focusing on the SSC and a senior participant in the study organized by the ASC, of which he is a co-founder. ”There is already strong evidence that these mutations converge on a much smaller number key biological functions. We now need to focus on these points of convergence to begin to develop novel treatments.

Autism, which is marked by deficits in social interaction and language development, as well as by repetitive behaviors and restricted interests, is known to have a strong genetic component. But until a few years ago, genomic research had failed to decisively associate individual genes with the disorder.

The two new studies highlight the factors that have radically changed that picture, State said. One is the advent of next-generation sequencing (NGS), which allows researchers to read each of the “letters” in the DNA code at unprecedented speed. Another is the establishment of the SSC; a 2007 study had suggested that de novo mutations would play a significant role in autism risk, and the SSC was specifically designed to help test that idea by allowing for close comparisons between children with autism and their unaffected parents and siblings. Lastly, collaborative initiatives such as the ASC are enabling teams of researchers around the world to work closely together, pooling their resources to create large datasets with sufficient statistical power to draw valid conclusions.

The large research teams behind each of the two new studies used a form of NGS known as “whole-exome” sequencing, a letter-by-letter analysis of just the portion of the genome that encodes proteins.

In November 2013, a study led by A. Jeremy Willsey, a graduate student in State’s lab, showed that the functional roles of the nine high-confidence autism risk genes that had then been discovered all converged on a single cell type in a particular place in the brain at a particular time during fetal development. Willsey is a co-author on both of the new Nature studies, which State believes will further accelerate our understanding of how the myriad of genes involved in autism affect basic biological pathways in the brain.

“These genes carry really large effects,” State said. “That we now have a bounty of dozens of genes, and a clear path forward to find perhaps hundreds more, provides an incredible foundation for understanding the biology of autism and finding new treatments.”

Gene therapy could be used to treat ADHD

A new study in the journal Nature may hold the key to combating attention deficit hyperactivity disorder: modifying your genes.

Researchers from the Massachusetts Institute of Technology and New York University’s Langone Medical Center found that ADHD is connected to the thalamic reticular nucleus, where your brain blocks out things that are distracting you. Working with mice, the team discovered that a gene mutation in some of the rodents meant the TRN wasn’t working properly — and that’s where things get interesting.

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X-Linked Recessive Inheritance

X-linked recessive inheritance is a mode of inheritance in which a mutation in a gene on the X chromosome causes the phenotype to be expressed (1) in males (who are necessarily homozygous for the gene mutation because they have only one X chromosome) and (2) in females who are homozygous for the gene mutation (i.e., they have a copy of the gene mutation on each of their two X chromosomes).

X-linked inheritance means that the gene causing the trait or the disorder is located on the X chromosome. Females have two X chromosomes, while males have one X and one Y chromosome. Carrier females who have only one copy of the mutation do not usually express the phenotype, although differences in X chromosome inactivation can lead to varying degrees of clinical expression in carrier females since some cells will express one X allele and some will express the other. The current estimate of sequenced X-linked genes is 499 and the total including vaguely defined traits is 983.

The most common X-linked recessive disorders are:

  • Red-green color blindness, a very common trait in humans and frequently used to explain X-linked disorders. Between seven and ten percent of men and 0.49% to 1% of women are affected. Its commonness may be explained by its relatively benign nature. It is also known as daltonism.
  • Hemophilia A, a blood clotting disorder caused by a mutation of the Factor VIII gene and leading to a deficiency of Factor VIII. It was once thought to be the “royal disease” found in the descendants of Queen Victoria. This is now known to have been Hemophilia B (see below).
  • Hemophilia B, also known as Christmas Disease, a blood clotting disorder caused by a mutation of the Factor IX gene and leading to a deficiency of Factor IX. It is rarer than hemophilia A. As noted above, it was common among the descendants of Queen Victoria.
  • Duchenne muscular dystrophy, which is associated with mutations in the dystrophin gene. It is characterized by rapid progression of muscle degeneration, eventually leading to loss of skeletal muscle control, respiratory failure, and death.
  • Becker’s muscular dystrophy, a milder form of Duchenne, which causes slowly progressive muscle weakness of the legs and pelvis.
  • X-linked ichthyosis, a form of ichthyosis caused by a hereditary deficiency of the steroid sulfatase (STS) enzyme. It is fairly rare, affecting one in 2,000 to one in 6,000 males.
  • X-linked agammaglobulinemia (XLA), which affects the body’s ability to fight infection. XLA patients do not generate mature B cells. B cells are part of the immune system and normally manufacture antibodies (also called immunoglobulins) which defends the body from infections (the humoral response). Patients with untreated XLA are prone to develop serious and even fatal infections.
  • Glucose-6-phosphate dehydrogenase deficiency, which causes non-immune hemolytic anemia in response to a number of causes, most commonly infection or exposure to certain medications, chemicals, or foods. Commonly known as “favism”, as it can be triggered by chemicals existing naturally in broad (or fava) beans.

Some scholars have suggested discontinuing the terms dominant and recessive when referring to X-linked inheritance due to the multiple mechanisms that can result in the expression of X-linked traits in females, which include cell autonomous expression, skewed X-inactivation, clonal expansion, and somatic mosaicism.

source

The Continuing Evolution of Genes

Each of us carries just over 20,000 genes that encode everything from the keratin in our hair down to the muscle fibers in our toes. It’s no great mystery where our own genes came from: our parents bequeathed them to us. And our parents, in turn, got their genes from their parents.

But where along that genealogical line did each of those 20,000 protein-coding genes get its start?

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Overhaul of our understanding of why autism potentially occurs

An analysis of autism research covering genetics, brain imaging, and cognition led by Laurent Mottron of the University of Montreal has overhauled our understanding of why autism potentially occurs, develops and results in a diversity of symptoms. The team of senior academics involved in the project calls it the “Trigger-Threshold-Target’’ model. Brain plasticity refers to the brain’s ability to respond and remodel itself, and this model is based on the idea that autism is a genetically induced plastic reaction. The trigger is multiple brain plasticity-enhancing genetic mutations that may or may not combine with a lowered genetic threshold for brain plasticity to produce either intellectual disability alone, autism, or autism without intellectual disability. The model confirms that the autistic brain develops with enhanced processing of certain types of information, which results in the brain searching for materials that possess the qualities it prefers and neglecting materials that don’t. “One of the consequences of our new model will be to focus early childhood intervention on developing the particular strengths of the child’s brain, rather than exclusively trying to correct missing behaviors, a practice that may be a waste of a once in a lifetime opportunity,” Mottron said.

Mottron and his colleagues developed the model by examining the effect of mutations involved in autism together with the brain activity of autistic people as they undertake perceptual tasks. “Geneticists, using animals implanted with the mutations involved in autism, have found that most of them enhance synaptic plasticity – the capacity of brain cells to create connections when new information is encountered. In parallel, our group and others have established that autism represents an altered balance between the processing of social and non-social information, i.e. the interest, performance and brain activity, in favor of non-social information,” Mottron explained. “The Trigger-Threshold-Target model builds a bridge between these two series of facts, using the neuro cognitive effects of sensory deprivation to resolve the missing link between them.”

The various superiorities that subgroups of autistic people present in perception or in language indicates that an autistic infant’s brain adapts to the information it is given in a strikingly similar way to sensory-deprived people. A blind infant’s brain compensate the lack of visual input by developing enhanced auditory processing abilities for example, and a deaf infant readapts to process visual inputs in a more refined fashion. Similarly, cognitive and brain imaging studies of autistic people work reveal enhanced activity, connectivity and structural modifications in the perceptive areas of the brain. Differences in the domain of information “targeted’’ by these plastic processes are associated with the particular pattern of strengths and weaknesses of each autistic individual. “Speech and social impairment in some autistic toddlers may not be the result of a primary brain dysfunction of the mechanisms related to these abilities, but the result of their early neglect,” Mottron said. “Our model suggests that the autistic superior perceptual processing compete with speech learning because neural resources are oriented towards the perceptual dimensions of language, neglecting its linguistic dimensions. Alternatively, for other subgroups of autistic people, known as Asperger, it’s speech that’s overdeveloped. In both cases, the overdeveloped function outcompetes social cognition for brain resources, resulting in a late development of social skills.”

The model provides insight into the presence or absence of intellectual disability, which when causative mutation alter the function of brain cell networking. Rather than simply triggering a normal but enhanced plastic reaction, these mutations cause neurons to connect in a way that does not exist in non-autistic people. When brain cell networking functions normally, only the allocation of brain resources is changed.

As is the case with all children, environment and stimulation have an effect on the development and organization of an autistic child’s brain. “Most early intervention programs adopt a restorative approach by working on aspects like social interest. However this focus may monopolize resources in favor of material that the child process with more difficulties, Mottron said. “We believe that early intervention for autistic children should take inspiration from the experience of congenitally deaf children, whose early exposure to sign language has a hugely positive effect on their language abilities. Interventions should therefore focus on identifying and harnessing the autistic child’s strengths, like written language.” By indicating that autistic ‘'restricted interests’’ result from cerebral plasticity, this model suggest that they have an adaptive value and should therefore be the focus of intervention strategies for autism.