GenFun

Click on the picture below to launch an app where you can see a bit about what you can and can't learn from your DNA, And if you have results from 23andMe or Ancestry.com, you can upload them and learn a bit about your DNA.

ALS genetics SNP

-A curious adult from the UK

February 27, 2017

The answer to your question is: no. The DNA change you are asking about is found more often in people with ALS, but not by much. In other words, having this bit of DNA does not mean you will for sure end up with ALS.

ALS stands for amyotrophic lateral sclerosis. It is a neurodegenerative disease of the neurons that control the movement of our muscles.

What is rs3849942(A;A)?

Our DNA is basically a long string of letters that our body reads to build and run each one of us. There are only four letters in that string: A, T, G, and C.

More than 99% of the time, we have the same sequence of letters as any other person on Earth. But since we’re all a little bit different from each other, we all have some changes in our DNA that are different from the next person.

Why would rs3849942 be linked to ALS?

Scientists aren’t really sure why this SNP is linked with ALS. It might just be close to a gene that plays a role in developing ALS. If the SNP is close enough to a gene like this, it shows up as linked to ALS.

The bottom line is: having the SNP doesn’t cause ALS. Many other factors play a role in who gets ALS. Not smoking, for example, could theoretically offset someone’s chance of getting ALS, even if they had the rs3849942 SNP.

Bioengineering immortality

-A curious adult from Ivory Coast

February 15, 2017

That’s a very interesting question! The short answer is no, probably not for humans.

The most likely reason we get old and die is that living takes a lot out of us. The buildup of damage over time causes us to break down and eventually die.

When I say “mistakes” I mean damage done to the instructions that let a cell do its job. These instructions are in a cell’s DNA.

DNA damage can happen when a cell makes a copy of itself. DNA damage can also happen when we come into contact with something called a mutagen.

Mutagens cause mutations, or changes, in our DNA. The longer we live, the more time we have to be exposed to mutagens.

Not Worth the Energy

It takes energy to stay alive. It also takes energy to fix DNA damage.

Sometimes our cells don’t have enough energy to do both. So like someone on a budget, a cell has to “decide” where to spend its energy.

Inheriting Kabuki syndrome

-A graduate student from the UK

February 7, 2017

Odds are that your husband isn’t a carrier for Kabuki syndrome because of how it is passed on. It tends to follow one of three patterns.

The most common way for people to end up with Kabuki syndrome is that it literally appears of out nowhere. Basically, the person’s DNA ends up with a new mistake in it that did not come from either parent. This kind of new mistake is called a de novo mutation. 

Most People Do Not Inherit Kabuki Syndrome

Kabuki syndrome is pretty rare. Only something like 1 in 32,000 newborns are born with it each year.

People with this condition can have a wide variety of symptoms in many parts of the body. They often have arched eyebrows or larger ears. Some will also have trouble with thinking and understanding, so special education can be helpful.  Click here to learn more about the symptoms associated with this condition.

Autosomal Dominant Kabuki syndrome

Mutations in the KMT2D gene cause around 75% of Kabuki syndrome cases that have symptoms. So this is the most common cause.

Like the majority of our genes, most everyone has two copies of KMT2D. We get one copy from mom and one copy from dad.

There only needs to be a problem or mutation in one copy of the KMT2D gene to cause Kabuki syndrome. This is called autosomal dominant inheritance.

Ethnicity DNA Percentages Not Solid

-A curious adult from Florida

January 31, 2017

If the 51% were a rock solid number then yes, both parents would have to have some Italian in their DNA. After all, you only get 50% of your DNA from one parent! At least 1% of your Italian heritage would have had to come from the other parent.

But in the real world of DNA ancestry testing, that percentage is a bit more wishy washy. I think of them as telling you that a sizeable part of your heritage looks Italian in the DNA test. Could be lower, could be higher.  

Parent and Child with 40% Italian

To understand how a parent whose DNA looks to be 40% Italian might have a child with the same percentage, we need to take a step back and review how DNA is stored in our cells. And how it is passed on.

DNA is stored in something called chromosomes. People usually have 46 of these.

These chromosomes come in nearly identical pairs. One from each pair comes from mom and one from dad.

Imagine these are the 23 pairs:

Ancestry.com

Ancestry.com has a very useful resource that gives you the likely range of your percent ancestry. In other words, it lets you know how reliable that 51% is and what its upper and lower limits are.

Let’s use my results as an example. If I click on a particular ancestry, the following image comes up:

This is a little hard to see so I will break it up into two separate images:

Third and fifth cousins DNA tests

-A curious adult from British Columbia

January 17, 2017

DNA can show they are related. You probably need a family tree to figure out the exact relationships. (Wikimedia Commons)

The table also gives you some idea about how many first, second and so on cousins you might expect to have. This is based on around 2-3 kids per generation and so doesn’t fit everyone’s situation but it does give you an idea about how the numbers increase. You probably have more than 100,000 seventh cousins for example.

What these tests are less precise about is the actual relationship. So sometimes the test will call someone as a third cousin when they may actually be a fifth cousin and so on. The more distant the relationship, the less precise the relationship assignment.

Let’s take an example where you’d think the test could pretty easily tell two people apart—first and second cousins.

Remember, first cousins should share 12.5% of their DNA while second cousins should share 3.125%. You can see these numbers in red in the table (1C is first cousin, 2C is second cousin).

In terms of cM, first cousins share, on average, 881 cM, while second cousins share 246 cM. These numbers are in the same ballpark as the percentages—first cousins share around four times as much DNA.

Somatic mutation mosaic

-A curious adult from Missouri

January 10, 2017

No it doesn’t. A change (or mutation) in the DNA of a muscle cell can’t be transferred to another muscle cell. Each cell has its own set of DNA.

The only way a mutation like this can spread (at least in people) is if it happens in a cell that makes copies of itself. Or if the mutation turns the cell into one that makes copies of itself.

Otherwise that lonely muscle cell in your finger will have a mutation that the rest of the cells in your body do not.

Early Mutations Can Spread

When a human being is first made, it is just a single cell! This single cell eventually divides over and over to become an adult with trillions of cells. These early cells are called stem cells.

During the early parts of human development, stem cells are very important. This is because just one of these stem cells will end up being many different kinds of cells in an adult.

Bacterial Sex Swaps DNA

Large organisms like humans are made out of many kinds of cells. Like cogs in a machine, all of those cells have to work consistently the way they were designed.

Humans also have DNA wound up in complicated structures called chromosomes for organization. It would be hard for the cells in our bodies to change up their DNA.

Smaller organisms that are just one single cell, like bacteria, often share and exchange DNA. This is easy for them because they can organize their DNA in little rings called plasmids.

Identifying incest with DNA

-A curious adult from Michigan

January 4, 2017

That’s an interesting question! It may actually be possible to get some idea about how related your parents are.

But you probably won’t able to say conclusively. The only way to know for sure would be to test the parents or another relative.

One way you can use your DNA to see if your parents might have been related is through a program like GEDmatch’s “Are your parents related?” app. 

DNA Mixes Between Generations

To understand how we can test someone’s DNA to check if their parents were closely related, we need to know a little more about how DNA works.

DNA has the instructions for making us. Since we all look a little bit different, it’s not surprising that our DNA is different, too.

Some people are tall and others are short, some have blue eyes and some have green or brown. These differences are coded in our DNA.

As you can see, only the child with related parents has any significant amount of this DNA. The child with the unrelated parents has none of these runs of homozygosity. This is because the chromosomes of the child with closely related parents are very similar to begin with.

Scientists can check for these regions in a person’s DNA, and count how many there are. Children born to unrelated parents will have relatively few of these areas.

DNA damage mutation usually harmless

-An undergraduate from France

December 13, 2016

The short answer is that UV rays can damage any part of our DNA. So we could get a mutation in a gene that could affect muscle movement.

Luckily for us, UV rays can only damage the DNA in cells they can reach: our skin cells. Our skin cells don’t actually use the muscle gene (see below), so a mutation in it wouldn’t matter for them. The gene in all of our muscle cells would still be fine.

1) Most of Our DNA Isn’t Instructions

DNA is like an instruction book for making a living thing. The most important parts of it are the genes. Each gene is like a specific instruction.

We can think of our DNA as a giant cookbook of recipes to make you. Each recipe is like a gene and tells us to do something important.

The most important mutations are usually the ones that happen in a gene. These can sometimes cause the gene to not work or work differently than usual.

DNA Changes and Skin Cancer

So our bodies have lots of layers of protection from mutations caused by UV rays.  But nothing is 100%. Sometimes those 2 eggs become 12 eggs in the recipe and our pancakes are ruined.

Luckily, only a very small percent of genetic changes from UV rays actually cause problems. Remember, for a mutation to cause damage, it needs to happen inside a gene, not get fixed, and cause a problem with a gene that that cell uses.

Parent children different blood type

-A curious adult from Michigan

December 6, 2016

While a child could have the same blood type as one of his/her parents, it doesn’t always happen that way. For example, parents with AB and O blood types can either have children with blood type A or blood type B. These two types are definitely different than parents’ blood types! 

But two O parents, for example, will pretty much always have O kids. They will match both parents.

Each specific instruction for a small part of you is called a gene. As humans, we all have the same 20,000 or so genes. What makes us different are the different versions of these genes.

For example, we all have the blood type gene, ABO. What gives us different blood types is that this gene comes in three different versions: A, B, and O. 

In a simple world, the three versions would give three blood types and a child would have one of the blood types of the parents. But we don’t live in a simple world, now, do we?

Gene-Protein Relationship

I told you there are all these different genes and that they come in versions. But what exactly do they do and what is different about them?

Genes are the instructions for proteins. And different gene versions make different versions of a protein. 

So the A version of the ABO genes makes the “A” version of a protein, the B version a B version of a protein and importantly, for our discussion, the O version doesn’t make either.

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