Haplogroup H sub-clades

For individuals that have tested their mtDNA and were classified under Haplogroup H, this new information is of tremendous impact in understanding the H Haplogroup phylogeography, and even more important for genealogists that search for the most recent possible common ancestors on their maternal line.

Our test is based on the most recent and comprehensive scientific research describing the topology of H haplogroup by Achilli et al. 2004 (link to the library). Upon ordering your test, your DNA will be tested for the following complete list of SNPs that are diagnostic for sub-Haplogroups H1-H15: 7028, 3010, 4769, 951, 750, 6776, 14365, 4336, 3915, 6869, 4793, 13101, 3591, 14470, 13759, 3936, 2259, 11377, 6253. Your final haplogroup designation will be made by the combined evaluation of the results of these positions and the HVR-I and II information that cover any position between 16001-16569 and 00073-00577 respectively.

The human mtDNA is made up of 16569 base pairs and can be divided into the coding region and the control region also known as the D-loop. The D-loop can be further divided into HVR-1 (Hyper variable control region 1) and HVR-2. Both the coding region and the D-loop are important to label a maternal lineage. In this paragraph and for the sake of simplicity, we will refer to the coding region and the D-loop as totally differently regions, although in reality the characteristics denoted to them herein overlap. The coding regions that evolve slowly carry mutation that have evoked only once through the homo-sapiens history. Therefore, it can be used to create the backbone of the mtDNA clades termed Haplogroups. Thus, individuals of African ancestry usually fall within the L macro Haplogroup, while individuals of Indian ancestry usually fall within the M macro Haplogroup. While this level of discrimination is well appreciated for describing a rough picture of humans and can illustrate mass movements of human migration, it lacks the ability to detail between lineages within each Haplogroup. In contrast, the D-loop is of specific importance for anthropological and genealogical purposes as it mutates in a higher rate than the coding region and therefore allows a more detailed variation and discrimination between maternal lineages. Therefore, an mtDNA lineage is appropriately labeled by a Haplogroup and then by the HVR-1 mutations of the specific lineage within the Haplogroup.

However, the two systems are not in disconnect and actually in many situations it is possible to infer from HVR-1 mutations the actual Haplogroup. Thus, for example, the combination of mutations 16224 and 16311 in the HVR-1 region usually means K Haplogroup that should further be confirmed by a specific coding region mutation such as 9055. However, while combining D-loop and coding region information have many advantages, it has also some pitfalls. One of the most important pitfalls for genealogists is the homoplasy or the convergence evolution problem. The region contains many "hot spots" that revert forward and backward often. Therefore, it is not often that the same HVR-1 motive can be found in two different Haplogroups and for that reason can represent very different phylogeographic scenarios. A good example can be the H Haplogroup as explained below.

H Haplogroup is one of the most frequent mtDNA Haplogroups. The first mtDNA to be sequenced in full belonged to an individual of European ancestry and by chance belonged to H Haplogroup (that can be expected if one recalls that H Haplogroup accounts for 40% of European mtDNAs), and its sequence was labeled as the Cambridge Reference Sequence (CRS). H Haplogroup is derived from HV* Haplogroup, and only two coding region mutations separate these Haplogroups, namely 2706 and 7028. As the CRS is the common motif within the Haplogroup there are no good HVR-1 markers that can point out to H Haplogroup compared to the K Haplogroup example, the only real way to confirm H Haplogroup is by testing a coding region mutation such as 7028. However, many authors, according to previous information, labeled all CRS or its one or two steps immediate derivatives as H Haplogroup, which creates two immediate problems:

1. CRS can appear under H, HV, U, U4, R, and therefore it is absolutely not possible to claim that two people that have CRS in common have a common recent ancestor. That would be an example for homoplasy between different Haplogroups.

2. Furthermore, even if two individuals are confirmed as H Haplogroup and both have CRS as their HVR-1 motif, does it really mean that they belong to the same recent lineage? No. As clearly suspected in the past, we now know that they can belong to very different H Haplogroup sub branches. That would be an example for homoplasy within the same Haplogroup.

Therefore the new paper is exciting as it finally enables us to break H Haplogroup into its sub-lineages answering three possible questions coming from genealogists:

* If I see my mutation in the chart pointing to a sub-clade why should I test? Answer: You see your HVR-1 mutations only! That can simply be the result of homoplasy (Remember it is a "hot spot" region!). You must confirm the sub-branch (when possible) with the coding region mutation that stands for a unique event polymorphism.

* If I don't see my mutation in the chart, how does this test work? What will it be verifying? Answer: HVR-1 or 2 does not show your coding region mutations. If we will take a look at H8 for example, we can see that it is separated from H* by one D-loop mutation and one coding region mutation. It is very possible that the D-loop mutation reverted to the ancestral state and if you will not check the coding region you will miss your Haplogroup. Furthermore, CRS can be found virtually everywhere within H.

* Is H Haplogroup a black hole? Answer: No, it is a well-defined Haplogroup with specific identifying coding region mutations. We treated it as a black hole as it covers 40% of the mtDNA in Europe. But now, having the novel H Haplogroup full sequences information we can clearly see that it is a well-organized Haplogroup with clear hierarchy.

In summary, digging for the truth and into one's mtDNA using HVR-1 motifs in the context of more and more coding region mutations is the answer and should not be avoided by those who are interested in their phylogenetic tree. State of the art labeling of a sample suspected as H, mandates the H confirmation test and then deep genotyping within H.

| top |

Family Tree DNA - Genealogy by Genetics, Ltd.
World Headquarters

1919 North Loop West, Suite 110 Houston, Texas 77008, USA
Phone: (713) 868-1438 | Fax: (832) 201-7147
Contact Us