I have written many blogs about phasing my own raw DNA. One of the things that was bothering me while going through the process was the presentation of the results. It is possible to phase millions of bases using the raw DNA results from one parent and at least 3 siblings. But once the DNA is phased, how can those results be best portrayed? In my previous Blog on the subject, I was able to figure out a fairly simple way to show my results, but the outcome was not totally satisfactory.
I liked how I was able to get the grandparents’ surnames at least in the first 2 bars. I also liked how I had a simple scale at the bottom. However, one of my bars went too far. Also, my simple chart started at zero and Chromosomes start at different positions. I was able to fix the bar going too far today. Excel makes these bars based on distance rather than positions, so one of my equations was wrong.
I told M MacNeill <email@example.com> of my concerns and he sent me his spreadsheet. One feature I really liked about the MacNeill Spreadsheet is that it had a place for cousin matches at the bottom. Below is the first Chromosome where I used my phased raw data from my mom and 3 other siblings to create a MacNeill Chart.
Sharon’s maternal first little segment didn’t work out perfectly, but that didn’t bother me. I know that the beginning and ends of Chromosomes can have small problematic segments. Note at the bottom that my match to Carolyn in yellow shows where my maternal crossover is in the upper part of the chart where I go from red to orange.
My Chromosome 10
I am looking at my Chromosome 10 because, for one thing, I have had trouble trying to visually phase this Chromosome in the past. Here is my attempt at visual phasing from early in 2016:
Here is another try including additional cousins that tested:
Note how different the maternal (lower) side is. I switched most of the maternal grandparents around.
Here is the MacNeill spreadsheet showing just the cousin matching part:
I have some good matches here. Blue is Hartley, green is Frazer, yellow is Lentz. Red is Rathfelder. This makes it clear that my chromosome is mapped wrong. I need more Hartley and Lentz. The above chart includes my brother who I had tested not too long ago.
Here is another try with my brother’s DNA results included:
My sister Sharon (S) has a better look now on her maternal side. I got rid of the small purple segment.
Looking At the Raw DNA Phasing – Paternal Side
I have two spreadsheet summarizing the results of the many hours of work it took to phase my family’s DNA from the raw data. One spreadsheet is for the paternal side phased DNA and the other is maternal. I have patterns for both sides. They are based on the order of my siblings: me (Joel), Sharon, Heidi and Jonathan. So an ABBB pattern would mean that Sharon, Heidi, and Jonathan all get their DNA from one grandparent, and I get mine from the other. Here is the paternal spreadsheet:
These patterns go logically one to the other. The first pattern goes from AABA to AAAA at position 2,605,158. The B changed to an A in Heidi position, so the crossover goes to her at that position. I have a column called GaptoNext. This is based on the number of tested SNPs between patterns. When this number is large, I suspect an AAAA pattern. That was the case above highlighted in yellow. Except there is a problem. To go from ABAB to AAAA means 2 changes, and there should only be one change (or crossover) at a time. This caused me to look at the bases.
A Paternal pattern missed
Here is what I found.
I had missed an AABA pattern at Build 36 Position 30,683,878. I took another look by setting my MS Access query so that Sharon and Heidi would have a different base from Dad:
This shows that the there is a change from ABAB to AABA even sooner than I thought between ID 400008 and 400045. This is an ID I created that sequentially numbers the tested SNPs. You can see another way I missed this pattern, because I didn’t fill in the missing bases. TTC? should be TTCT. CCT? should be CCTC.
What does the missing pattern represent?
The pattern of ABAB TO AABA is actually my crossover (Joel). It is a bit more difficult to see than the others. That is because the ABAB pattern is the same as BABA. The change of BABA to AABA is my change of the first B to the first A. Naturally, I put myself in the first position. In rough terms, that gives me a paternal crossover at about position 30.5M. This is a good location as it does not interfere with a large match that I have with an unknown paternal DNA relative named Shamus:
Here is my corrected Dad Pattern for Chromosome 10:
I have gone from 6 to 8 crossovers as the previous correction lead to another one. I also took out one of Heidi’s crossovers that I had wrongly identified. So fixing one problem fixed a lot of others. It helps to describe the start and stop of each pattern and to describe each crossover. The important results are the person and the last Position column. These show who the crossover belongs to and where that crossover occurs on the chromosome. I then entered the paternal crossover results into the MacNeill Spreadsheet and got this:
I took out the large space between the siblings. The problem is that the space is now the same as between the maternal and paternal phased part for each sibling. Excel has no happy medium that I’ve found.
The blue is Hartley and green is Frazer. The raw phasing in the upper part of the chart matches with the cousin matches below. It is interesting that some of the cousin matches define the crossovers. For example, the Jim to Sharon match gives Sharon’s crossover. Also the Paul to Sharon match gives Sharon’s other crossover. The Paul to Jonathan match gives Jon’s first crossover.
The Maternal Side
Hopefully resolving the maternal phasing will be easier than the paternal side. My visual phasing only showed four crossovers. Here is my unfinished spreadsheet showing 5 crossovers (under the Person column):
Here, it looks like I already added an AAAA pattern to the end. That was because the AABA pattern ended at about 114M and the Chromosome itself ends at about 135M. My GapstoNext column showed that gap as almost 20,000 SNPs. My question now is: should I add an AAAA pattern to the beginning also? Perhaps. An AAAA pattern means that 4 siblings match and all got their DNA in that area from their maternal (in this case) grandmother. Those results were consistent with how I had the visual phasing done. In fact, the visual phasing indicated that the 4 siblings should all get their maternal DNA from the Lentz side up until about 60M. Let’s take a closer look. This gets at my first note above in the spreadsheet image. There were only 3 single SNPs showing the AAAB pattern and they were spaced a long way apart – over 10 Megabases each. In this case, I will disregard those 3 widely spaced patterns as some type of mistake and stay with the AAAA pattern. Once I made the change from the AAAA pattern to the AAAB pattern, that brings us up to about 60M for my (Joel’s) first crossover. That seems to fit well. That leaves us with 4 crossovers – one per sibling as opposed to the two per sibling on the paternal side.
First I’ll compact the Gedmatch browser results, then show the raw DNA Phasing results on the MacNeill Chart:
When I compare the results, I see a problem I had with the visual phasing. The next to the last crossover looked to belong to Sharon, but instead it belonged to Heidi. Also Jon’s second paternal crossover should have been marked as an “F” above. That was just a typo. The third J for Joel crossover that I had above was not a crossover. In the middle, the 2 close crossovers of J and S should be instead S and J if I’m reading the MacNeill Chart correctly. It looks like all the FIRs and HIRs, etc. match. Once I did the raw DNA phasing, it is obvious how the gedmatch browser results had to match the raw DNA phasing results. Before, I did the raw DNA phasing it was not so obvious.
I’m happy with the results. I get to pick whatever colors I want for the four grandparents. It still would be nice to have some sort of labels or color key. After a hard day of phasing DNA, it is rewarding to see the results displayed so nicely. Thank you Mr. MacNeill.
A few observations:
- The 4 siblings did not inherit any Rathfelder DNA (brown) on the left side of Chromosome 10
- Lentz DNA (yellow) is missing from the right side of the Chromosome for the same 4 siblings
- As I have my mother’s DNA results, that would make up for the missing DNA from those 2 maternal grandparents
- Short segments of Hartley DNA (blue) are missing near the beginning and near the end of the Chromosome (i.e. none of the four siblings inherited Hartley grandfather DNA in those areas).
- M MacNeill has the best display that I am aware of for mapping phased DNA.
- The final mapping is like the final exam where previous mistakes are brought out, but there is a chance to correct them.
- The phasing process is difficult, but there are built in checks and balances to find and correct mistakes or missed patterns.
- The raw DNA phasing procedure (I use the Athey method) would generally be used if a parent has been tested and the visual one is used if a parent has not been tested. However, the visual phasing as developed by Kathy Johnston is important to use as a framework for the raw DNA phasing as well as a check for the end result.
- The raw DNA phasing results appear to be better than what I was able to get using the visual phasing. Not because the visual phasing method is bad; more because I have not mastered it.
- If you are using someone else’s spreadsheet, it is a good idea to know how they work in case anything goes wrong.
- After writing many blogs on visual and raw data DNA phasing, it is nice to see everything come together using the MacNeill Spreadsheets and Charts.