Heffernan DNA Project
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You do not have to be a molecular biologist to enter the world of genetic genealogy, but it does help to understand some of the basics. What follows is a simple explanation of the DNA testing used in the Heffernan DNA Project and some of the science behind it, and how this testing can be used as an aid in genealogical research. Actually, you will see that the term genetic genealogy is somewhat of a misnomer since it is not our genes that actually get tested but instead the filler junk DNA in between our genes. There are several Wikipedia links in the text for you to follow if you desire to read more detailed and technical information on specific terms and topics.
If you remember back to junior high science class or high school biology or health class, our physical blueprint is contained in our DNA which is organized into 46 chromosomes (23 pairs), identical copies of which are found in the nucleus of almost every cell in our body. For each chromosome pair, we inherit one chromosome from our father and one from our mother. Of these 23 pairs, there is one special pair called the sex chromosomes that control the gender-specific aspects of our body. The mother of a child always contributes an X chromosome to the sex pair. The father, on the other hand, contributes either another X chromosome to the pair in which case a child becomes a female (XX) or a Y chromosome in which case a child becomes a male (XY). Of the 46 chromosomes, the Y chromosome has the unique property of being passed down virtually unchanged from father to son. Thus, a man has virtually an exact copy of his father's Y chromosome and his father's father's Y chromosome, etc. X chromosomes and all of the other chromosomes that are inherited from each parent are not exact copies of any of the parents' chromosomes but are random constructions of genes and DNA, and thus are not as useful for genealogical purposes—at least at this time. So, just as a boy inherits his father's surname, he also inherits his father's Y chromosome. This is what makes testing of the Y chromosome (Y-DNA testing) useful in researching the direct paternal line and tracing surname lineages and why it is the type of DNA testing used in the Heffernan DNA Project and in all surname-based genealogical DNA projects. And, since only males have the Y chromosome, this is also why only males can be Y-DNA tested for this and other surname-based projects. However, there is another type of DNA testing (mtDNA) that does involve females and can be an aid to genealogical research, although it is not particularly helpful in surname-based genealogical research—see the Maternal Line Ancestry section below.
This narrows the DNA testing down to just one of our 46 chromosomes, the male Y chromosome. But exactly what on the Y chromosome gets tested? All of our chromosomes, including the Y chromosome, consist of a few genes (about 2-3% of our DNA) with vast amounts of filler DNA (about 97-98% of our DNA) in between the genes. This filler DNA is also known as junk DNA and has no known function. So, along with the genes on the Y chromosome which a boy inherits from his father also comes all this filler DNA being passed down virtually unchanged from generation to generation. Within these filler regions are certain known locations (loci) where a short segment of DNA will stutter, repeating itself a number of times. This is known as a Short Tandem Repeat (STR) and its location is called a marker. This is what makes testing of the Y chromosome (Y-DNA testing) useful in researching the direct paternal line and tracing surname lineages and why it is the type of DNA testing used in the Heffernan DNA Project and in all surname-based genealogical DNA projects. An STR on the Y chromosome is referred to as a Y-STR and the marker is identified using a DNA Y-chromosome Segment (DYS) number (e.g., DYS390). These Y-STRs are what get tested in a genealogical Y-DNA test. The Y-STR DNA test involves counting the number of repeats (yielding what is called an allele value) at selected DYS markers. The results from a DNA testing company consist of an allele value (number of repeats) for each of the DYS markers tested. Although there is quite a bit of overlap among testing companies, each one offers slightly different testing packages that include the testing of slightly different sets of DYS markers. A set of these DYS marker allele values for a particular person is called their haplotype.
So how is the DNA collected for testing? There is no blood drawn, no visits to a doctor or lab, and no real inconveniences of any kind. The testing company mails out a test kit that includes a couple of cheek swabs and the consent form—view FTDNA's test kit. The testee simply follows the instructions for scraping the inside of their cheek and re-packaging the swabs, signs the consent form, and mails the kit back to the testing company. The Y-STR DNA test results are typically received within two to four weeks. Most companies offer to keep the DNA sample in storage so further testing can be ordered at a later date without the need to send in another sample.
Now, how do these Y-STR DNA test results help us with our genealogy? On its own, a male's haplotype (his particular set of DYS marker allele values) is not of much genealogical value. It is when the haplotypes of two or more people are compared that biological relationships are revealed (or disproved) and genealogists are aided in constructing their family history with a higher degree of certainty. The more DYS markers that have been tested and the more allele values that match, the closer people are likely to be related and the fewer generations back to their most recent common ancestor (MRCA). The reason for this is that although the filler DNA is passed down virtually unchanged, a DYS marker allele value (number of repeats) can change (mutate) every once in a great while when being passed down from a father to his son. When one of these changes occurs, this mutation and corresponding changed allele value are subsequently handed down to all direct male line descendants of that son. So, if two men have a recent MRCA, say the same grandfather, then their haplotypes (sets of allele values) are very likely to be identical or almost identical since in only two generations there is unlikely to have been any mutations at any of the DYS markers tested. However, if the MRCA for two men is 40 generations back (about 1200 years), then their haplotypes will likely show some mismatches since over the course of 40 generations there is likely to have been some mutations occur in each man's line going back to that MRCA. Therefore, if a researcher wants to know if their Heffernan line is connected to another Heffernan line, then a Heffernan male descendant from each line could be Y-STR DNA tested to either confirm or deny to a high degree of probability whether they share a common Heffernan ancestor within the not-too-distant past.
This has been a very simplified explanation of how genetics and DNA testing are used for genealogy research. To read other or more in-depth explanations, see the Resource section below.
The goal of the Heffernan DNA Project is to obtain Y-STR DNA test results from as many males representing as many Heffernan lines as possible in the U.S., Ireland, U.K., Canada, and elsewhere. These results will be used to build a Heffernan DNA database of individual haplotypes and build average haplotypes (modal haplotypes) for each of the various Heffernan lines and their progenitors. This will provide a way of verifying traditional genealogical research (and perhaps opening new leads) that links present-day people to one of the Heffernan ancestral lines. Also, previously unknown relationships between some of the old Heffernan lines may be discovered in the course of the project. So, if you are a Heffernan male or know one who would be willing to do the testing, please visit the project join page for more details.
DNA testing is performed for a variety of reasons besides genealogical research—such as forensic testing, medical testing, and paternity testing. Different types of DNA testing are used for each of these different purposes. Genealogical Y-STR DNA testing examines a few STR markers in the filler (junk) DNA portion of a male's Y chromosome. Other types of DNA testing look at other markers on any of our 46 chromosomes.
Genealogical Y-STR DNA testing is NOT the same as forensic DNA testing. Also known as genetic fingerprinting, forensic testing is what one commonly hears about in police investigations and sees on tv programs such as CSI. These DNA tests are designed to generate genetic profiles that are highly unique to each individual. The FBI's CODIS database is the primary forensic DNA datatbase used by law enforcement across the country. CODIS uses 13 highly variable genetic markers from several different chromosomes to generate the unique genetic profiles. None of these 13 markers are on the Y chromosome and thus are not used in genealogical Y-STR DNA testing. Although genealogical Y-STR DNA testing uses more markers than CODIS, these markers are not as variable and don't generate a necessarily unique genetic profile (haplotype). Several people can share the same genetic profile from Y-STR DNA testing which is what helps tie people and family lines together.
Genealogical Y-STR DNA testing is NOT the same as medical DNA testing. Medical testing usually aims at diagnosing genetic disorders and involves looking at the active gene portions of our chromosomes. Genealogical Y-STR DNA testing examines tiny sections from the filler (junk) DNA of the Y chromosome which does not yield any direct information about the active genes of the Y chromosome. Genealogical testing therefore can not reveal anything about genetic disorders caused by abnormalities in genes on other chromosomes or on the Y chromosome, with one possible exception. Genealogical testing that tests the DYS464 marker of the Y chromosome and find that this marker is missing may indicate possible infertility in the male tested. Even though the DYS464 marker itself is part of the filler DNA and not involved in male fertility, it is near a gene that is. However, this missing DYS464 is a rare occurence and would require futher testing to confirm any infertility. Plus, if the test subject has already fathered children then it a moot issue. But, overall, there is nothing about any possible genetic disorders or any physical characteristics that can be gleaned from the results of a genealogical Y-STR DNA test. I have even posted my 43-marker Y-STR DNA test results openly in public databases.
Genealogical Y-STR DNA testing is NOT the same as paternity DNA testing. Paternity tests are designed to be much more precise and to conclusively prove whether a particular individual is the parent of a particular child. The markers used are spread out over several of the 46 chromosomes and not confined to the Y chromosome as with genealogical testing. However, genealogical testing can reveal some unexpected male family relationship facts. If two brothers take the same genealogical DNA test, it could be shown that they don't have the same father. Likewise, if a father and a son take the same genealogical DNA test, it could be shown that they are not father and son. Nothing is revealed regarding any family relationships involving females.
The genealogical Y-STR DNA testing described above is the primary DNA testing used in genetic genealogy to aid genealogists in their traditional genealogical research of paternal line ancestry, and it is the primary DNA testing used in the Heffernan DNA Project. However, there are a couple of other types of DNA testing that can be used to reveal other things about one's ancestry.
Besides being used to aid traditional genealogical research, DNA testing is also used in a branch of physical anthropology called human population genetics. This field of study seeks to define the distinct human populations from which we came and to understand their geographic origins and migration history based on the analysis of DNA from modern-day people around the world. One of the current ongoing studies in this field is the highly publicized National Geographic Genographic Project which is collecting and analyzing DNA from thousands of people all over the world. Traditional genealogy can only reach back as far as the written records exist—maybe a thousand years or so at most. Human population genetics picks up where traditional genealogy leaves off and can give us a glimpse into our deep ancestry of the ancient past.
Population geneticists have divided humanity's paternal line history into a hierarchy of populations called haplogroups, each with a distant common male ancestor and defined by a unique tiny mutation on the Y chromosome called a Single Nucleotide Polymorphism (SNP). These SNPs (pronounced snips) are little blips where a single letter (molecule) in the DNA sequence has changed (mutated). As with a Y-STR mutation, one of these single-letter mutations at any given location in the Y-DNA (called a Y-SNP) occurs very infrequently and when it does occur it is passed down to all subsequent male line descendants. When testing is performed, unlike Y-STR testing which counts the number of repeats for a given STR, Y-SNP testing simply tests whether a given Y-SNP is present or not—positive or negative. For example, a test result of M170+ means that Y-SNP M170 is present; a test result of S21- means that Y-SNP S21 is not present.
Y-DNA research has resulted in a hierarchy consisting of 18 major Y-haplogroups (sometimes called clades) identified by letters A through R, and subgroupings (sometimes called subclades) identified using numbers and lower case letters (e.g., R1b1c9). Some of the major Y-haplogroups are descended from (i.e., a subgroup of) another Y-haplogroup. This hierarchy of clades and subclades forms a Y-haplogroup tree (see the Y-DNA Haplogroup Tree 2006) which is constantly being revised as a result of ongoing research. Each major Y-haplogroup and subgrouping in the Y-haplogroup tree is characterized by its own unique Y-SNP(s), often has a characteristic DYS marker haplotype pattern, and is usually associated with a particular geographic origin and migration history. For example, testing positive for Y-SNP M207 (M207+) would put one in Y-haplogroup R; then testing M173+ would further refine it to Y-haplogroup R1; and then testing M343+ puts one in Y-haplogroup R1b; and further testing could refine the Y-haplogroup further. R1b is the most common Y-haplogroup in western Europe and is thought to have originally formed on the Iberian Penninsula (Spain), later migrating out to populate much of western Europe, including the British Isles. Other common Y-haplogroups include R1a1, associated with Eastern Europe and central Asia; I, found throughout Europe and very common in Scandanavia; and Q, predominant among Native Americans.
A male's Y-STR DNA test results can be a good predictor of his upper level Y-haplogroup (such as R1b). This prediction is usually included in the test results sent back from testing companies. However, it is not necessarily conclusive and does not narrow the Y-haplogroup to one of the lower level subclades (such as R1b1c9). To conclusively establish the Y-haplogroup to the greatest level of specificity currently possible, Y-SNP testing needs to be done. Most of the companies that offer Y-STR DNA testing also offer Y-SNP DNA testing for prices ranging from about $50 to over $200. New Y-SNPs are being discovered all the time creating new branches on the Y-haplogroup tree, some being associated with very specific geographic regions. Some of these new Y-SNPs are proprietary for a period of time to the company that discovered them and only that company has the ability to test for them. One of the leading Y-SNP research and testing companies is EthnoAncestry, although their Y-STR testing is not really adequate for genealogical purposes at this time.
Testing for paternal line deep ancestry via Y-SNP DNA testing does not provide much (if any) help with traditional genealogical research and is not necessary for participation in the Heffernan DNA Project. It is for anyone that is interested in perhaps discovering a little more about their ancient ancestry beyond the reach of genealogy. If anyone in the Heffernan DNA Project does decide to do Y-SNP testing, their results can certainly be included on the Project Results page. Keep in mind that if someone in a Heffernan line has already done the Y-SNP testing, results for all other males in that line will almost assuredly be the same. In that case, it may be better to use the funds to help have a distant Heffernan cousin Y-STR tested, or to contribute to the project's General Fund which helps subsidize testing for Heffernan males. See the project join page for more details on getting Y-SNP tested and on contributing to the General Fund.
The DNA testing described thus far, Y-STR and Y-SNP testing, has restricted the researching to the direct paternal line and limited the testing to males only. But alas, biology has also provided a DNA mechanism for researching the direct maternal line (the mother's mother's mother's ... mother's line) and allows for the testing of both males and females. All 46 human chromosomes, including the Y chromosome, reside in the nucleus of each cell in the body and contain one's core DNA. However, outside the nucleus in each cell exist little energy-producing organelles called mitochondria which have their own DNA completely separate from the chromosomal DNA. This mitochondrial DNA (mtDNA) has the unique property of being inherited solely from the mother. Whereas the Y chromosome is passed down virtually unchanged from father to son, mtDNA is passed down virtually unchanged from mother to all her children—both sons and daughters. Like Y-DNA, mtDNA mutates over time, although at a slower pace than Y-DNA. These features make mtDNA an ideal tool for genealogical research of the direct maternal line. Click here to view a Y Chromosome & mtDNA Flow diagram.
For genealogical mtDNA testing, the actual DNA sequence is determined and the results consist of a long list of letters. There are two hypervariable regions of mtDNA (called HVR1 and HVR2) that are more prone to mutation and show more variance in the population. These HVR1 and HVR2 regions of mtDNA are the ones typically tested and sequenced by testing companies. Results from mtDNA testing can be used to determine if two people (male or female) share a recent direct maternal line ancestor—the closer the match, the fewer generations back to the maternal line MRCA. Like Y-DNA testing, mtDNA testing can be used to explore the deep ancestry of the direct maternal line. Test results will include assignment to one of the mtDNA haplogroups which are not the same as Y-haplogroups. Like Y-haplogroups though, mtDNA haplogroups are organized into a hierarchical tree and each haplogroup is associated with a particular geographic origin and migration history.
Genealogical mtDNA testing is offered by many of the companies that do Y-DNA testing and typically costs $100-$200. Some companies even offer full mtDNA sequencing for $400-$500. DNA collection for mtDNA testing is the same as for Y-DNA testing and males can often order both Y-STR and mtDNA testing at the same time. Anyone wishing to be mtDNA tested can join one of the existing mtDNA projects, many of which are geographic based. Find mtDNA projects at: Family Tree DNA, World Families Network, or Google search for projects. If you are a Heffernan male doing your Y-DNA testing through the Heffernan DNA Project or if you are a Heffernan female by birth or have a Heffernan female in your direct maternal line, you can do your mtDNA testing through the Heffernan DNA Project if you like—see the project join page for more details.
There are many places on the web to learn more about genetic genealogy and DNA testing. Doing a Google search on genetic genealogy will list numerous web sites. Below are links to some good sites, along with some books, where you can learn more on genetic genealogy and DNA testing.