Did you notice something new on your Y DNA results page at Family Tree DNA this week? If not quite yet, you will soon if you have taken the Big Y test. There’s a surprise waiting for you. You can sign in here to take a look.
The first thing you might notice is that the Big Y has been renamed to the Big Y500. However, the results I want you to take a look at aren’t under the Big Y500 tab, but on your regular Y DNA Y-STR Results tab. Click to take a look
In the past, 5 panels of Y DNA STR markers have been available:
- Panel 1 – 1-12 markers
- Panel 2 – 13-25 markers
- Panel 3 – 26-37 markers
- Panel 4 – 38-67 markers
- Panel 5 – 68-111 markers
Now, a 6th panel has been added:
- Panel 6 – 112-550 markers
However, there is a difference between the first 5 panels and the 6th panel.
Why is it Called the Y500?
If there is a total of 550 markers reported, why is this product called the Y500?
That’s a great question with an even greater answer.
Family Tree DNA actually tests for a total of 550 markers. Values for markers between 112 and 550 are provided FOR FREE when you take a Big Y test.
Family Tree DNA guarantees that you will receive at least a total of 500 markers, or they will rerun your Big Y test at no cost to you to obtain enough additional markers to reach 500. (The 500 number assumes that you have all 111 STR markers. If you have not tested all of the STR panels, the number will be lower by the number of STR values you haven’t tested. This means that if you took the Y67, but not the Y111, your 500 guarantee number would be 500-44, where 44 is the number of markers in the Y111 panel that you have not yet ordered.)
The best part?
The markers above 111 are ENTIRELY FREE with a Big Y test – for both existing customers who have already taken that test, and all future customers too. Yes, you read that right. If you took the Big Y previously, you are receiving the markers in panel 6, 112-550 absolutely free.
How does it get better than free?
The Big Y Uses a Different Technology
There is a difference between the first 111 markers and the markers from 112-550, meaning that they are read using different technologies
The results for the first 111 STR markers are produced using a technology that targets these specific areas and is very accurate.
The results for the 112-550 markers is produced using next generation sequencing (NGS) on a different testing platform than the Y-111 results. NGS, utilized for the Big Y, scans the Y chromosome rather than targeting specific locations. This scanning process is repeated several times, with values at specific locations recorded.
Using NGS technology, your DNA is scanned multiple times, with the number of scans, such as 25 or 30, referred to as the coverage level. The goal is for multiple/most/all scans to find the same value at the same location consistently. Because of the nature of scanning technology, this sometimes doesn’t happen, for various reasons, including “no-calls” which is when for some reason, the scans simply can’t get a reliable read at that location in your DNA. No calls are typical and occur at low levels in everyone’s scan.
Here’s an example from a Big Y scan viewing the actual results using the Big Y chromosome browser.
The blue bars are forward reads and the green bars are reverse reads. Dark blue and dark green bars indicate high quality scans. Medium blue and green are medium quality scans and faintly colored bars indicate poor quality. If you take a look at where the little black arrow at the top is pointing, you can see that a T is the expected value at that location.
When the expected value as determined in the human reference genome is found at that location, nothing is recorded in that column. However, when a different result is discovered, like A in this case, it’s noted and highlighted with pink. We can see that there are 5 As on forward and reverse strands of high quality, then a low quality read, 6 more high quality reads, followed by two reads that show the expected value (nothing recorded) and then three more high quality A reads.
The goal is to determine what actual value resides at that location, and when that value is determined, it’s referred to as a “call.”
For a “call” to be made, meaning the determination of the actual value in that position, the person or software making the call must take several quality factors into consideration.
In this case, the number of high quality reads indicating the derived (mutation) value of “A” allows this location to be definitively called as “A.” Because several other men previously tested have A at this location, a SNP name has already been assigned to this mutation – in this case, A126 in haplogroup R.
However, if you look to the right and left of the arrow to the next two browser locations that contain mutations, you can see in both cases that there are less than half of the column locations that are marked as pink with derived values (mutations), meaning those not expected when compared to the reference model.
These types of locations which are neither clearly ancestral (reference model) nor derived values are when value judgements come into play in terms of deciding which value, the ancestral or derived, is actually present in the DNA of the person being tested.
Some people will call a SNP with only one mutation reported out of 20 or 30 scans. Some people will call a SNP with 2 scans; some with 5, and so forth. Generally, Family Tree DNA uses a minimum threshold of 5 high quality scans to call a mutation value.
Now, let’s talk about how STR values, meaning results displayed in those locations between 112-550, are found in your Big Y NGS data file. You can read about the difference between SNPs and STRs in the article, STRs vs SNPs, Multiple DNA Personalities.
Short tandem repeats, known as STR values, are the numbers reported in your STR panels. These are stutters of DNA, kind of like the copy machine got stuck in that one area for a few copies.
For example, in haplogroup R, for this person, the value of 13, meaning 13 repeats of a particular sequence, is found at marker DYS393.
Repeated sequences are in essence inserted in-between SNPs in some DNA regions, and the number of repeats reported in STR marker panels is the number of stutters, or repeats, of a particular repeated sequence.
That sounds simpler than it is, because how to count a sequence isn’t always the same. Let’s look at an example showing 20 consecutive DNA positions.
The actual values are shown in the value row. However, these values can be counted in a number of different ways. I’ve also added a “stray read” at location 13 which causes confusion.
At location 13, we show a value of G which does not fit into the repeat pattern. How do we interpret that, and what do we do with it?
The repeat pattern itself is a matter of where you start counting, and how you count.
I’ve color coded the repeats with blue and yellow. Incomplete repeats are red. The stray G in location 13 is green, because it breaks the repeat sequence.
In example 1, we start counting with T in position 1, and there are clearly 3 repeated groups of TACG before we hit our stray G in position 13, which stops the repeat pattern. However, after the stray G, there is one more full repeat sequence of TACG. Do we ignore the G and count the 4th TACG as part of the group, or do we count only the first 3 complete TACG sequences? The total number of repeats could be counted as either 3 or 4, depending on how we interpret the stray G in location 13.
In example 2, we start counting with the GTAC, because I was simulating a reverse read where we start at the end and work backwards. In this case, we clearly have 2 reads, then our stray G which occurs in the middle of a read. Do we ignore that stray G and call the rest of the blue GTAC surrounding the G as a repeat? That blue repeat group is followed by another yellow group. Do we count it at all, or do we simply stop with the marker count of 2 because the G is in the way and breaks the sequence? This repeat sequence could be counted as either 2, 3 or 4, depending on what you do with the G and the following sequence group, both.
Examples 3 and 4 follow the same concept and have the same questions.
All STR sequences face the issue of where to start reading. Where you begin reading can affect the number of repeat counts you wind up with, even without our stray G in position 13.
STR markers obtained from NGS sequencing face this same challenge, but it’s complicated by the issue of no-reads and the call variance that we saw in the chromosome browser where the same location is sometimes called differently on different scans, meaning we really can’t tell which is the actual value. What do we do with those?
All of this is complicated by the fact that some regions of the Y chromosome simply do not produce valid or reliable information. Different (groups of) people define this unreliable region as starting and ending in different locations. Therefore different people analyzing the same information often arrive at different answers to the same question or use marker locations that others don’t.
I suspect all of this may fall into the category of trivia you never wanted to know, but now you’ll understand why you may find different (sometimes strongly held) opinions of what is “right” when two geeky types are arguing strongly about a particular STR value as your eyes glaze over…
Here’s the bottom line – if you’re using results called by the same vendor, you don’t have to worry about whether you and someone else are being accurately compared. You and everyone else at that vendor will have your results reported using the same technology and calling methodology.
Family Tree DNA has always taken a more conservative approach, because they only want to report to customers what they know to be accurate.
You will not see low confidence values on your reports, nor calls from an unreliable region. Genealogists cannot reach reliable genealogical conclusions using unreliable data.
The Big Y 500
Because of the nature of scanned STR results, Family Tree DNA can’t guarantee that you will have a reliable read at every location. In fact, few people will have values at every location. The technology for the Y-111 markers provides a very high level of accuracy and Family Tree DNA will provide results for every 1-111 location unless you actually have a deletion, meaning no DNA in that location. However, the values of markers 112-550 are taken from the Big Y NGS scan.
Therefore, some Big Y customers will have a few markers above 111 that show a “-“ instead of results, such as FTY945 and FTY1025, shown below. A value of “0” found in markers 1-111 means that there is actually no DNA in that location, and it’s not a read error. No DNA at a specific location is heritable, meaning it can serve as a line-marker mutation, while a “no call” means that the scan couldn’t read that genetic address. No calls cannot be compared to others and should be ignored.
Before someone starts to complain about having markers with “no reads,” remember that Family Tree DNA is providing up to 439 additional markers available FOR FREE to customers who have taken (or will take) the Big Y test.
That’s right, there is no charge for these new markers. You are guaranteed 389 additional markers, but you may actually receive as many as 439, depending on how well your DNA reads. The kits I’ve checked have only been missing a couple of marker values, so these kits received 437 additional markers, far above the guaranteed 389.
Right now, matching is not included for the 112-550 markers. Matching above 111 markers may be challenging because while Family Tree DNA does guarantee that you’ll have at least 389 new marker values, those won’t be the same markers above 111 for everyone. In a worst-case scenario, you could mismatch with someone on as many as 100 markers above 111 panel, simply because both you and the person you are matching against are both missing 50 different markers each, for a total of 100 markers mismatching.
Additionally, not everyone has tested all 111 STR markers, and you will receive your 112-550 values if you have taken the Big Y test regardless of whether or not you’ve tested all 111 STR markers.
Matching on the first 111 markers is reliable because you will have an accurate value, even if the value is 0. Having no DNA at a specific location is a valid result and can be compared to other testers.
With different markers between 112 and 550 missing for different men, matching becomes very tricky. Specifically, how do we interpret mismatches? How many mismatches to we allow to still be considered a reasonable match?
Matching is an entirely different prospect when integrating the markers between 112 and 550 into the equation with a potential of up to 100 mismatching locations in that range simply from no-reads.
I had presumed that Family Tree DNA would offer matching on these additional markers. Presume is a dangerous word, I know. Matching is not offered right now, and given the complexities, I don’t know if matching as we know it will be the future or not, how reliable it would be, or how Family Tree DNA would compensate for the missing STR information that differs with each person’s test.
Furthermore, I’m not quite sure what they would do with two men who haven’t both tested to the same STR level, meaning panels 1-5, but have taken the Big Y so have values for 112-550.
Big Y Purchases
Here’s the status of Big Y tests, today:
- New Big Y purchase if you have done no Y DNA testing at all – you will now be able to purchase a Big Y without having to previously purchase any STR markers. The 111 STR markers are now bundled into the Big Y purchase, which makes the Big Y appear more expensive than before when the STR markers had to be purchased separately before you could order a Big Y test. The Big Y plus all 111 STR markers is now $649 during the DNA Day Sale, regularly $799.
- Already tested through 111 STRs – the Big Y is only $349 on sale right now, and $449 regularly, both significantly discounted from just a few months ago.
- Existing customers who have taken some level of Y STR test but not the Big Y – will have to upgrade their STR test to the 111 level when ordering the Big Y. Those tests are discounted appropriately, shown in the table below.
- Existing customers who have not tested their STR markers to 111, but have already taken the Big Y – will receive marker values from 112-550. However, they will only receive the Y STR markers below 112 for panels they have paid for. This means that if you have only tested to 37 markers, you will have results for locations 1-37, not for 38-111, but will have results for locations that read from 112-550. This would be the perfect time to upgrade so that you have a complete marker set.
Right now, Family Tree DNA is having their DNA Day Sale and it’s a great time to purchase a Big Y or to upgrade your STR markers if you don’t have the full 111. The sale pricing shown is valid through April 28th. You can click here to order.
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