Y Chromosome Haplotype Reference Database
The Y Chromosome Haplotype Reference Database (YHRD) is an open access, annotated collection of population samples typed for Y chromosomal sequence variants. Two important objectives are pursued: (1) the generation of reliable frequency estimates for Y-STR Haplotypes and Y-SNP Haplotypes to be used in the quantitative assessment of matches in forensic and kinship cases and (2) the characterization of male lineages to draw conclusions about the origins and history of human populations. Since its creation in 1999 it has been curated by Lutz Roewer and Sascha Willuweit at the Institute of Legal Medicine and Forensic Sciences, Charité - Universitätsmedizin Berlin. The database is endorsed by the International Society for Forensic Genetics (ISFG) and partially funded by Life Technologies and Promega Corporation. By November 2018 265,324 9-STR locus haplotypes, among them 205,059 17-STR locus haplotypes, 50,692 23-STR locus haplotypes, 42,506 27-STR locus haplotypes and 23,109 Y SNP profiles sampled in 135 countries have been directly submitted by forensic institutions and universities from 72 countries. In geographic terms, 40.6 % of the YHRD samples stem from Asia, 27.0 % from Europe, 16.5 % from North America, 11.8 % from Latin America, 3.0 % from Africa and 1.0 % from Oceania/Australia (release 59 from Nov 1, 2018). The 1251 individual sampling projects are described in more than 480 peer-reviewed publications 
YHRD is built by direct submissions of population data from individual laboratories. Upon receipt of a submission, the YHRD staff examines the originality of the data and assigns an accession number to the population sample and performs quality assurance checks. The submissions are then released to the public database, where the entries are retrievable by Search for haplotypes, populations, contributors or accession numbers. All population data published in forensic journals as FSI: Genetics or International Journal of Legal Medicine are required to be validated by the YHRD custodians and are subsequently included in the YHRD.
The database supports the most frequently used Haplotype formats (e.g. Minimal (minHt), Powerplex Y12, YFiler, Powerplex Y23  , YfilerPlus and Maximal (maxHt) for which differently-sized databases exist.
Because strong correlations between geographic areas and Y chromosomal variants exist, the YHRD population database was structured to display the geographic, linguistic and phylogenetic relationship of searched haplotype profiles. Currently the YHRD database recognizes four separate "metapopulation" structures: national, continental, linguistic/ethnic and phylogenetic affiliation with several categories within. In population genetics the term metapopulation describes discrete spatially distributed population groups which are interconnected by geneflow and migration. By analogy, the term metapopulation is used in forensic genetics to describe a set of geographically dispersed populations with shared ancestry and continuing geneflow. Thus, the population groups are more similar within the metapopulation than to groups outside the metapopulation.
The concept of pooling data to build "national databases" has a very straightforward explanation: law enforcement agencies and forensic services rely on their national population to build reference databases. In most instances offenders and victims stem from the national population, and their genetic profiles should thus be represented in the database. In countries like USA, Brazil, UK or China which are characterized by strong population substructure national reference databases are often built on basis of a historical concept of ethnic affiliation, e.g. the US population is sub-structured in a Caucasian, African, Hispanic, Asian and Native American populations or UK differentiates English, Afro-Caribbean, Indo-Pakistani and Chinese. National databases due to their importance in national legislation are thus searchable in the YHRD. Each national Metapopulation in the YHRD comprises all individuals sampled in a particular country regardless of the ancestry of the individuals.
Continental Metapopulations in the YHRD comprises all individuals sampled in a particular continent regardless of their ancestries. The YHRD defines seven continental Metapopulations following the United Nations classification of geographical regions: Africa, Arctic, Asia, Europe, Latin America, North America, Oceania/Australia.
The Metapopulation structure built on basis of "ethnicity/linguistic affiliation" takes to a larger extent the ancestry of sampled individuals into account. "Ancestry" is a term collating historical, cultural, geographical and linguistic categories. Of course, a Metapopulation concept on basis of "ethnicity" is by no means ideal, fully rational or fully translatable, but simply takes the fact into account that on a global level categories other than "nation" or "geography" far better describe the observed genetic clustering and inhomogeneity of Y chromosome patterns.
For a global reference database the "major language group" criterion seems most appropriate to group data by taking the ancestry into account and produce subdatabases with respect to genetic similarity. The reasoning in doing so is twofold: first, language is an inherited cultural trait and thus the language phylae often correlate with genetic traits not the least to Y chromosome polymorphisms. Second, since languages are well examined by science and mostly understood by the public due to the long tradition of language research, the linguistic terminology is in principal more understandable and translatable into practice than their genetic pendant. Aside from the pure linguistic categorization (e.g. the Altaic language family comprising people speaking Turk and Mongol languages) we took also unifying geographic criteria (Sub-Saharan Africa comprising speakers of different African language groups which live south of the Sahara).
It is important to state, that the current Metapopulation structure is an a-priori categorization which needs a continuous evaluation and verification by means of statistical methods to quantify the genetic similarity/dissimilarity between the samples. While the current categorization of eight large Metapopulations gains some support from genetic distance analysis done on basis of ~41,000 Haplotypes  a further subdivision of the "Eurasian - European Metapopulation" was implemented solely on basis of Y-STR Haplotypes. The analysis of ~12,000 European Haplotypes by AMOVA demonstrates that three larger pools of European Haplotypes exist: the Western, the Eastern and the Southeastern Metapopulation.
Currently the YHRD has seven non-overlapping metapopulations: African, Afro-Asiatic, Amerindian, Australian Aboriginal, East Asian, Eskimo-Aleut, and Eurasian. Some of these metapopulations are further subdivided, e.g. Eurasian into six subcategories, from which European subgroup splits further into three groups of Western, Eastern and Southeastern Europeans.
The DNA profiling of Y chromosomes submitted to the YHRD is now continuously extended for binary Y-SNP polymorphisms. The phylogeny of the Y chromosome defined by binary polymorphisms is well established and stable (Underhill et al. (2000), Hammer et al. (2001), Jobling and Tyler-Smith (2003) and Karafet et al. (2008)). All Y chromosomes sharing a mutation are related by descent, until a further mutation splits the branch. Haplotypes within a haplogroup could be highly similar or even "identical by descent" (IBD). In thus, the haplogroup could be used as a criterion to substructure the database according to the phylogenetic descent of samples. Even though the chronology of the SNP mutations is far less certain than the structure of the tree, many haplogroups could be equated with events in human prehistory. The worldwide distribution of the patterns of the human Y-chromosome diversity has revealed clear geographically associated haplogroups (Underhill et al. (2000)).
Analysis of molecular variance (AMOVA) is a method for analyzing population variation using molecular data, e.g. Y-STR Haplotypes. With AMOVA it is possible to evaluate and quantify the extent of differentiation between two or more population samples. AMOVA is implemented as an online tool in the YHRD and provides a way of estimating ΦST and FST values. The online tool accepts Excel files and creates entry files from it. As much as 9 reference populations selected from the YHRD as well as population sets can be added to the AMOVA analysis. The online calculation returns as a result a *.csv table with pairwise FST or ΦST(RST) values plus p-values as a test for significance (10,000 permutations). In addition, an MDS plot is generated to illustrate the genetic distance between the analyzed populations graphically. The program shows the references for the selected population studies which facilitates the correct citation.
The tool can be applied for forensic cases when a mixed trace (2 or more male contributors) should be analyzed. The result will be a likelihood ratio of donorship vs. non-donorship of the putative contributor to the trace.
The tool can be applied for kinship cases when a relationship between upstream and downstream relatives (e.g. father-son or grandfather-grandson) should be analyzed. The result will be a likelihood ratio (or kinship index) of patrilineal relationship vs. patrilineal non-relationship of the analyzed persons.
Searching the YHRD will result in a match or a non-match between a searched haplotype and the databased reference samples. The relative number of matches is described as the profile frequency. In forensic casework the probability of a match which is based on the profile frequency is evaluated using different methods. Some of these are recommended by national guidelines, e.g. the augmented counting method with confidence intervals and/or theta subpopulation correction (SWGDAM Interpretation Guidelines for Y-Chromosome STR typing by Forensic Laboratories in the USA, 2014) or the Discrete Laplace method (Andersen et al. 2013) as recommended in Germany (Willuweit et. al. 2018). Both augmented counting and DL values are provided by the YHRD for different metapopulations.
|August 1, 1999||1||2,517||YHRD 1.0|
|June 16, 2000||1a||3,589|
|January 1, 2003||2||18,050|
|August 18, 2003||3||19,482|
|October 30, 2003||4||20,152|
|July 11, 2003||5||20,320|
|October 12, 2003||6||20,865|
|December 29, 2003||8,9||21,446|
|February 24, 2004||10||21,546|
|February 26, 2004||11||22,872|
|April 13, 2004||12||24,524||YHRD 2.0|
|May 24, 2004||13||25,066|
|July 1, 2004||14||26,325|
|September 18, 2004||15||28,649|
|December 17, 2004||16||32,196|
|May 31, 2005||17||34,558|
|October 14, 2005||18||38,761|
|January 31, 2006||19||41,965|
|August 1, 2006||20||46,831|
|December 28, 2006||21||51,253|
|April 13, 2007||22||52,655|
|August 10, 2007||23||54,833|
|July 23, 2008||24||59,004||YHRD 3.0|
|October 1, 2008||25||65,165|
|January 29, 2009||26||68,108|
|February 13, 2009||27||72,082|
|March 23, 2009||28||72,055|
|June 12, 2009||29||74,742|
|August 21, 2009||30||79,147|
|November 16, 2009||31||81,099|
|December 18, 2009||32||84,047|
|March 3, 2010||33||86,568|
|July 16, 2010||34||89,237|
|December 30, 2010||35||91,601|
|May 15, 2011||36||93,290|
|June 21, 2011||37||97,575|
|December 30, 2011||38||99,881|
|February 17, 2012||39||101,055|
|August 29, 2012||40||104,174|
|October 1, 2012||41||105,498|
|January 11, 2013||42||108,949|
|January 18, 2013||43||112,005|
|July 12, 2013||44||114,256|
|October 31, 2013||45||124,343|
|December 20, 2013||46||126,931|
|August 15, 2014||47||132,553||YHRD 4.0|
|November 10, 2014||48||136,184|
|February 17, 2015||49||143,044|
|July 18, 2015||50||154,329|
|January 6, 2016||51||160,693|
|October 27, 2016||52||178,171|
|March 01, 2017||53||183,655|
|June 06, 2017||54||188,209|
|October 20, 2017||55||197,102|
|April 9, 2018||56||207,467|
|June 15, 2018||57||216,562|
|September 9, 2018||58||255,811|
|November 1, 2018||59||265,324|
- Y Chromosome
- Population Genetics
- DNA profiling
- Short Tandem Repeat
- Single Nucleotide Polymorphism
- List of online databases
- "YHRD Homepage". Retrieved November 1, 2018.
- "FSIGEN Publishing Guidelines" (PDF). Retrieved 25 September 2013.
- "Promega PowerPlex Y". Retrieved 25 September 2013.
- "Applied Biosystem Yfiler". Retrieved 25 September 2013.
- "Promega PowerPlex Y23". Retrieved 25 September 2013.
- Hanski, I. and Gilpin, M. (1997). Metapopulation Biology: Ecology, Genetics, and Evolution., Academic Press, San Diego.
- Willuweit, S., Roewer, L. and The International Forensic Y Chromosome User Group (2007). Y chromosome haplotype reference database (YHRD): Update., Forensic Sci Int Genet 1(2): 83--87.
- Roewer, L., Croucher, P. J. P., Willuweit, S., Lu, T. T., Kayser, M., Lessig, R., de Knijff, P., Jobling, M. A., Tyler- Smith, C. and Krawczak, M. (2005). Signature of recent historical events in the european y-chromosomal STR haplotype distribution., Hum Genet 116(4): 279--291.
- Roewer, L., Kayser, M., Dieltjes, P., Nagy, M., Bakker, E., Krawczak, M. and de Knijff, P. (1996). Analysis of molecular variance (AMOVA) of y-chromosome-specific microsatellites in two closely related human populations., Hum Mol Genet 5(7): 1029--1033.