Its often said that humans are 99.9% identical. and what makes us unique is a measly 0.1% of our genome. This may seem insignificant. But what these declarations fail to point out is that the human genome is made up of three billion base pairswhich means 0.1% is still equal to three million base pairs.

In those three million differences lie the changes that give you red hair instead of blonde, or green eyes instead of blue. You can find changes that increase your risk of obesity, or others that decrease your risk of heart disease; differences that make you taller or lactose intolerant, or allow you to run faster.

When I first started learning about genetic variation, I assumed these changesthe 0.1% that make us uniqueonly appeared in certain places, such as genes for height or inherited diseases like diabetes. I thought the rest of the genomethe other 99.9%was fixed; that the 0.1% that was different in me was more or less the same 0.1% that was different in you. But, as it turns out, the 0.1% of DNA that is different between people is not always the same 0.1%: Variation can happen anywhere in our genomes.

In fact, one group of scientists looking at 10,000 people found variants at 146 million unique positions, or about 4.8% of the genome. Another group collected the DNA from 15,000 people and found 254 million variants, roughly 8% of the genome. And as we continue to sequence 100,000, 100 million, or all seven billion people on the planet, we will find a lot more variation. This means that humans have many more differences than we first thought.

Imagine that your DNA is a car. There are certain obvious variants you can have: blue or white, two-door or four-door, convertible or sedan. These changes represent the 0.1%. Because the other 99.9%the engine, the seats, the steering wheel, the tireshas to be there for the car to work, we assume they are fixed.

But electric cars have shown us that we dont need the gas cap, the gas tank, or even a gas engine any more; we can replace those things with a variant like batteries and charging ports. And maybe one day well develop cars that have boosters instead of tires so we can hover over the ground.

In other words, what we believe is static may actually be variable. More than 0.1% of the car can change and it still be a car, just like the human genome.

With the rise of services that offer to sequence your DNA, more and more people are talking about the value of personal genomics and what you might uncover about yourself. These kinds of mail-in tests are an easy way to point to something tangiblelike your blue eyes or the waddle you and your grandmother shareand say It runs in the family. You might even say, Theres a gene for that!

But those examples of straight-forward, visible evidence are just starting points in the immense and only partially explored field of personal genomics. There are also many variations of our genomes that are invisible to the naked eye, like the way we metabolize caffeine, have a distaste for cilantro, or the more serious examples of predispositions toward certain types of cancers and diseases like Alzheimers and Parkinsons.

There are also all sorts of other gene variants we havent discovered yet. Because our data is limited by the amount of sequenced DNA available for study, scientists like myself have only explored a small portion of the genetic variation that exists in the world.

As access to personal genomics becomes a more practical option and more people opt in to research, this data pool grows every day. This means our theories will become much less theoretical in the months and years to come, and it soon wont be surprising to discover theres a gene for almost every trait.

So what does all this variation actually mean? What do we learn by cataloging all this information?

The consequences of sequencing millions of peoples DNA and identifying new genetic variants are both simultaneously predictable and unknown. On the predictable side, we are going to learn a lot more about human health and disease: Individual genetic variants and groups of genetic variants will be found to play a role in obesity, heart disease, and cancer, among other factors. We are going to find genetic variants responsible for rare diseases that have gone undiagnosed.

But its the unknown findings that get me excited. We dont know how many unique variants we will find. And while our current understanding of biology suggests some positions in DNA are not variable (because any change in these genes disrupts the basic function of being human), we may discover that these positions actually are variable and can change. Were also getting to a point where we will be able to better study the role of environmentwhat you are exposed to, the things you choose to eat, the activities you decided to engage inand how it interacts with your DNA. With this information, we will be able to better make predictions about you as an individual.

There is still so much for us to discover about human genetic variation. A variant that increases risk for a disease today might turn out to be protective for another disease tomorrow. The more people who get their DNA sequencedwhether for personal or research purposesthe more we will discover.

We each carry three billion base pairs of information inside us with the potential to unravel a piece of the mystery that makes us all so fundamentally human. At the end of the day, we are all still more similar than we are differentbut we are just beginning to understand how important our differences are.

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Genetics has proven that you're uniquejust like everyone else - Quartz

How Cannabis Strain Genetics Influence the THC:CBD Ratio

Whydo strains like Blue Dream and Harlequin have such different effects? In large part, its because they have very different THC-to-CBD ratios.

THC and CBD are the two most abundant cannabinoids in most strains. THC is well known as the major psychoactive compound. CBD is best known for having a wide range of medical uses. While CBD lacks the psychoactive properties of THC, it does influence the effects of THC in the brain. This is why the THC:CBD ratio strongly influences a strains effects, and why that ratio is important when deciding which strain is right for you.

Heres the cool part: The THC:CBD ratio is largely determined by strain genetics. Each plants genetic code determines the way the plant produces the two compounds. Its a fascinating process that many consumers arent aware of.

THC and CBD are both made from another cannabinoid called cannabigerol (CBG). Within Cannabis plants, each of these compounds is actually present in a slightly different, acidic form. The plants are really making either THCA or CBDA out of CBGA (Figure 1). Its only after THCA and CBDA are decarboxylatedby heat that we get significant levels of THC and CBD. The heat energy from your vaporizer, lighter, or oven causes a chemical reaction that turns THCA and CBDA into THC and CBD, respectively.

THCA and CBDA dont have the same effects as their activated (decarboxylated) counterparts. Remember that scene in Super Trooperswhere the guy eats a bag of cannabis flower and goes out of his mind? That wouldnt really work, because flower contains mostly THCA, which isnt psychoactive. You would have to heat the flower at the right temperature first, turning the THCA into THC, before eating it would get you high.

A single CBGA molecule can turn into a single THCA or CBDA molecule, but not both. How does the plant decide which to make? That depends on the presence of an enzyme that comes in two flavors. Lets call them Enzyme 1 (E1) and Enzyme 2 (E2).

E1 takes CBGA and converts it into CBDA, while E2 converts CBGA into THCA (Figure 1). Some strains only have E1, some only have E2, and some have both.

Like most plants and animals, Cannabis plants inherit two copies of their genes (although there are rare exceptions to this). As it turns out, the E1 and E2 enzymes that turn CBGA into either CBDA or THCA are encoded by two different versions of the same gene. Because each plant gets two copies of that gene, there are only three possibilities: A plant can have two copies of the gene that encodes the E1 enzyme, it can have one copy each of the genes that encode E1 and E2, or it can have two copies of the gene that encodes E2 (Figure 2).

Importantly, these three possibilities are based solely on the THC:CBD ratio, and dont take into account other compounds that a particular strain might produce. The three broad THC:CBD ratio strain categories are:

Cannabis genetics limit THC and CBD production so that only these three broad categories of flower are possible. Hemp strains do not produce significant levels of THC, while most commercial strains fall into the high-THC categorythey have THC but negligible levels of CBD. Mixed strains produce both THC and CBD, but generally not as much THC as high-THC strains or as much CBD as the more potent hemp strains.

In the next article of this series, we will explore more precisely what the limits on THC and CBD levels are for each of these categories. Later on, well consider some of the effects you may experience when consuming strains with different THC:CBD ratios.

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How Strain Genetics Influence THC:CBD Ratios | Leafly - Leafly

How does one set of genes result in huge horns in males and none at all in females?

Picture a lion: The male has a luxuriant mane, the female doesnt. This is a classic example of what biologists call sexual dimorphism the two sexes of the same species exhibit differences in form or behavior. Male and female lions pretty much share the same genetic information, but look quite different.

Were used to thinking of genes as responsible for the traits an organism develops. But different forms of a trait mane or no mane can arise from practically identical genetic information. Further, traits are not all equally sexually dimorphic. While the tails of peacocks and peahens are extremely different, their feet, for example, are pretty much the same.

Understanding how this variation of form what geneticists call phenotypic variation arises is crucial to answering several scientific questions, including how novel traits appear during evolution and how complex diseases emerge during a lifetime.

So researchers have taken a closer look at the genome, looking for the genes responsible for differences between sexes and between traits within one sex. The key to these sexually dimorphic traits appears to be a kind of protein called a transcription factor, whose job it is to turn genes on and off.

In our own work with dung beetles, my colleagues and I are untangling how these transcription factors actually lead to the different traits we see in males and females. A lot of it has to do with something called alternative gene splicing a phenomenon that allows a single gene to encode for different proteins, depending on how the building blocks are joined together.

Over the years, different groups of scientists independently worked with various animals to identify genes that shape sexual identity; they realized that many of these genes share a specific region. This gene region was found in both the worm gene mab-3 and the insect gene doublesex, so they named similar genes containing this region DMRT genes, for doublesex mab-related transcription factors.

These genes code for DMRT proteins that turn on or off the reading, or expression, of other genes. To do this, they seek out genes in DNA, bind to those genes, and make it either easier or harder to access the genetic information. By controlling what parts of the genome are expressed, DMRT proteins lead to products characteristic of maleness or femaleness. They match the expression of genes to the right sex and trait.

DMRTs almost always confer maleness. For instance, without DMRT, testicular tissue in male mice deteriorates. When DMRT is experimentally produced in female mice, they develop testicular tissue. This job of promoting testis development is common to most animals, from fish and birds to worms and clams.

DMRTs even confer maleness in animals where individuals develop both testes and ovaries. In fish that exhibit sequential hermaphroditism where gonads change from female to male, or vice versa, within the same individual the waxing and waning of DMRT expression results in the appearance and regression of testicular tissue, respectively. Likewise, in turtles that become male or female based on temperatures experienced in the egg, DMRT is produced in the genital tissue of embryos exposed to male-promoting temperatures.

The situation is a little different in insects. First, the role of DMRT (doublesex) in generating sexual dimorphism has extended beyond gonads to other parts of the body, including mouthparts, wingspots and mating bristles aptly named sex combs.

Secondly, male and female insects generate their own versions of the doublesex protein through whats called alternative gene splicing. This is a way for a single gene to code for multiple proteins. Before genes are turned into proteins, they must be turned on; that is, transcribed into instructions for how to build the protein.

But the instructions contain both useful and extraneous regions of information, so the useful parts must be stitched together to create the final protein instructions. By combining the useful regions in different ways, a single gene can produce multiple proteins. In male and female insects, its this alternative gene splicing that results in the doublesex proteins behaving differently in each sex.

So in a female, instructions from the doublesex gene might include sections 1, 2 and 3, while in a male the same instruction might include only 2 and 3. The different resulting proteins would each have their own effect on what parts of the genetic code are turned on or off leading to a male with huge mouthparts and a female without, for instance.

How do male and female forms of doublesex regulate genes to produce male and female traits? Our research group answered this question using dung beetles, which are exceptionally numerous in species (over 2,000), widespread (inhabiting every continent except Antarctica), versatile (consuming about every type of dung) and show amazing diversity in a sexually dimorphic trait: horns.

We focused on the bull-headed dung beetle Onthophagus taurus, a species in which males produce large, bull-like head horns but females remain hornless. We found that doublesex proteins can regulate genes in two ways.

In most traits, it regulates different genes in each sex. Here, doublesex is not acting as a switch between two possible sexual outcomes, but instead bestowing maleness and femaleness to each sex independently. Put another way, these traits dont face a binary decision between becoming male or female, they are simply asexual and poised for further instruction.

The story is different for the dung beetles head horns. In this case, doublesex acts more like a switch, regulating the same genes in both sexes but in opposite directions. The female protein suppressed genes in females that would otherwise be promoted by the male protein in males. Why would there be an evolutionary incentive to do this?

Our data hinted that the female doublesex protein does this to avoid what is known as sexual antagonism. In nature, fitness is sculpted by both natural and sexual selection. Natural selection favors traits increasing survival, whereas sexual selection favors traits increasing access to mates.

Sometimes these forces are in agreement, but not always. The large head horns of male O. taurus increase their access to mates, but the same horns would be a hassle for females who have to tunnel underground to raise their offspring. This creates a tension between the sexes, or sexual antagonism, that limits the overall fitness of the species. However, if the female doublesex protein turns off genes that in males are responsible for horn growth, the whole species does better.

Our ongoing research is addressing how doublesex has evolved to generate the vast diversity in sexual dimorphism in dung beetles. Across species, horns are found in different body regions, grow differently in response to different quality diets, and can even occur in females rather than males.

In Onthophagus sagittarius, for instance, its the female that grows substantial horns while males remain hornless. This species is only five million years diverged from O. taurus, a mere drop of time in the evolutionary bucket for insects. For perspective, beetles diverged from flies about 225 million years ago. This suggests that doublesex can evolve quickly to acquire, switch, or modify the regulation of genes underlying horn development.

How will understanding the role of doublesex in sexually dimorphic insect traits help us understand phenotypic variation in other animals, even humans?

Despite the fact that DMRTs are spliced as only one form in mammals and act primarily in males, the majority of other human genes are alternatively spliced; just like insects doublesex gene, most human genes have various regions that can be spliced together in different orders with varying results. Alternatively spliced genes can have distinct or opposing effects based on which sex or trait theyre expressed in. Understanding how proteins that are produced by alternatively spliced genes behave in different tissues, sexes and environments will reveal how one genome can produce a multitude of forms depending on context.

In the end, the humble dung beetles horns can give us a peek into the mechanisms underlying the vast complexity of animal forms, humans included.

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What dung beetles are teaching us about the genetics of sex differences - The Conversation US

Spinal Muscular Atrophy (SMA) is a genetic disease that affects the nervous system and causes weakness of the voluntary muscles, impacting movement. On Tuesday, March 28, Evenings with Genetics, a monthly speaker series hosted by Baylor College of Medicine and Texas Childrens Hospital, will highlight a new drug that has been approved by the FDA to treat the disease.

Dr. Timothy Lotze, associate professor of pediatrics neurology at Baylor and director of the Pediatric MDA Clinic at Texas Childrens, will speak about this new drug, called Nusinersen, the first drug to be found to be effective in the treatment of SMA, and how it will impact patient outcomes in the future. Lotze will be joined by a special guest speaker, the mother of the first patient in Texas to be treated with the drug, who will detail their journey to treatment.

Spinal muscular atrophy is a progressive neurodegenerative disease and has been a common genetic cause of infant death, as well as causing progressive weakness in many children and teenagers. Once an incurable disease, a newly developed treatment is saving the lives of these patients and starting a new era of gene therapy for pediatric neurological disease, Lotze said.

The Evenings with Genetics series offers current information regarding care, education and research as they relate to genetic disorders and encourages networking within the community by connecting patients and their families with others in similar situations.

The program is free and open to the public, but registration is required. The seminar will be held at the Childrens Museum of Houston, 1500 Binz St., 77004. Light refreshments will be provided beginning at 6:30 p.m., and the seminar will begin at 7 p.m. For more information, please call 832-822-4280 or visit theevents registration page.

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New SMA treatment topic of March Evenings with Genetics - Baylor College of Medicine News (press release)