Unique event polymorphism
Encyclopedia
In genetic genealogy
a unique-event polymorphism (UEP) is a genetic marker
that corresponds to a mutation which is likely to occur so infrequently that it is believed overwhelmingly probable that all the individuals who share the marker, worldwide, will have inherited it from the same common ancestor, and the same single mutation event.
Generally, UEP is an allele
for which all copies derive from a single mutation
al event.
In genetic genealogy the mutations considered to be UEPs can be any germline mutation
usually single-nucleotide polymorphisms – the replacement of one letter by another in the DNA sequence, and the terms UEP and SNP are often loosely used interchangeably. But UEPs may also be large-scale additions, such as the YAP insertion which defines Y-DNA haplogroups D
and E
, inversion or deletions.
The discovery and widespread testing of new UEPs has been the key to the increasingly detailed analysis of the patrilineal and matrilineal ancestry of mankind into ever more precise family trees of Y-DNA, mtDNA haplogroup
s. UEPs in X
and autosomal
chromosomes are also used to trace genealogy extending time ranges available for Y-DNA and mtDNA.
sequences (STRs), the other main type of genetic variation made use of in genealogical DNA test
ing.
Unlike UEPs, STR sequences are highly variable, and there is a significant probability that one of a set may have changed its repeat number after only a few generations. That makes a particular STR haplotype
much more specific, matching a much smaller number of people. It also means, at least in the case of Y-STR
markers, that quite unrelated lineages may have converged to the same combination of Y-STR markers entirely independently by different routes.
Exceptionally, there are a few cases where Y-STR markers can take on the status of UEPs, typically where a large-scale deletion event may have occurred, causing a sudden big change in the Y-STR repeat number rather than the usual single increment or decrement, which can be considered to have been a unique one-off in a group of lineages. Such a change in the Y-STR
DYS413 for example distinguishes subgroup J2a1 from J2a in Y-DNA haplogroup J
.
Genetic genealogy
Genetic genealogy is the application of genetics to traditional genealogy. Genetic genealogy involves the use of genealogical DNA testing to determine the level of genetic relationship between individuals.-History:...
a unique-event polymorphism (UEP) is a genetic marker
Genetic marker
A genetic marker is a gene or DNA sequence with a known location on a chromosome that can be used to identify cells, individuals or species. It can be described as a variation that can be observed...
that corresponds to a mutation which is likely to occur so infrequently that it is believed overwhelmingly probable that all the individuals who share the marker, worldwide, will have inherited it from the same common ancestor, and the same single mutation event.
Generally, UEP is an allele
Allele
An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...
for which all copies derive from a single mutation
Mutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
al event.
In genetic genealogy the mutations considered to be UEPs can be any germline mutation
Germline mutation
A germline mutation is any detectable and heritable variation in the lineage of germ cells. Mutations in these cells are transmitted to offspring, while, on the other hand, those in somatic cells are not. A germline mutation gives rise to a constitutional mutation in the offspring, that is, a...
usually single-nucleotide polymorphisms – the replacement of one letter by another in the DNA sequence, and the terms UEP and SNP are often loosely used interchangeably. But UEPs may also be large-scale additions, such as the YAP insertion which defines Y-DNA haplogroups D
Haplogroup D (Y-DNA)
In human genetics, Haplogroup D is a Y-chromosome haplogroup. Both D and E lineages also exhibit the single-nucleotide polymorphism M168 which is present in all Y-chromosome haplogroups except A and B, as well as the YAP unique-event polymorphism, which is unique to Haplogroup...
and E
Haplogroup E (Y-DNA)
In human genetics, Haplogroup E is a human Y-chromosome DNA haplogroup. Haplogroup E is one of the two main branches of the older Haplogroup DE, the other main branch being haplogroup D. The E clade is divided into two subclades: E1 and E2 .-Origins:Underhill et al. proposed that haplogroup E...
, inversion or deletions.
The discovery and widespread testing of new UEPs has been the key to the increasingly detailed analysis of the patrilineal and matrilineal ancestry of mankind into ever more precise family trees of Y-DNA, mtDNA haplogroup
Haplogroup
In the study of molecular evolution, a haplogroup is a group of similar haplotypes that share a common ancestor having the same single nucleotide polymorphism mutation in both haplotypes. Because a haplogroup consists of similar haplotypes, this is what makes it possible to predict a haplogroup...
s. UEPs in X
X chromosome
The X chromosome is one of the two sex-determining chromosomes in many animal species, including mammals and is common in both males and females. It is a part of the XY sex-determination system and X0 sex-determination system...
and autosomal
Autosome
An autosome is a chromosome that is not a sex chromosome, or allosome; that is to say, there is an equal number of copies of the chromosome in males and females. For example, in humans, there are 22 pairs of autosomes. In addition to autosomes, there are sex chromosomes, to be specific: X and Y...
chromosomes are also used to trace genealogy extending time ranges available for Y-DNA and mtDNA.
Comparison with short tandem repeats (STRs)
The properties of UEPs can be contrasted with those of short tandem repeatShort tandem repeat
A short tandem repeat in DNA occurs when a pattern of two or more nucleotides are repeated and the repeated sequences are directly adjacent to each other. The pattern can range in length from 2 to 5 base pairs and is typically in the non-coding intron region...
sequences (STRs), the other main type of genetic variation made use of in genealogical DNA test
Genealogical DNA test
A genealogical DNA test examines the nucleotides at specific locations on a person's DNA for genetic genealogy purposes. The test results are not meant to have any informative medical value and do not determine specific genetic diseases or disorders ; they are intended only to give genealogical...
ing.
Unlike UEPs, STR sequences are highly variable, and there is a significant probability that one of a set may have changed its repeat number after only a few generations. That makes a particular STR haplotype
Haplotype
A haplotype in genetics is a combination of alleles at adjacent locations on the chromosome that are transmitted together...
much more specific, matching a much smaller number of people. It also means, at least in the case of Y-STR
Y-STR
A Y-STR is a short tandem repeat on the Y-chromosome. Y-STRs are often used in forensics, paternity, and genealogical DNA testing.-Nomenclature:Y-STRs are assigned names by the HUGO gene nomenclature committee....
markers, that quite unrelated lineages may have converged to the same combination of Y-STR markers entirely independently by different routes.
Exceptionally, there are a few cases where Y-STR markers can take on the status of UEPs, typically where a large-scale deletion event may have occurred, causing a sudden big change in the Y-STR repeat number rather than the usual single increment or decrement, which can be considered to have been a unique one-off in a group of lineages. Such a change in the Y-STR
Y-STR
A Y-STR is a short tandem repeat on the Y-chromosome. Y-STRs are often used in forensics, paternity, and genealogical DNA testing.-Nomenclature:Y-STRs are assigned names by the HUGO gene nomenclature committee....
DYS413 for example distinguishes subgroup J2a1 from J2a in Y-DNA haplogroup J
Haplogroup J (Y-DNA)
In human genetics, Haplogroup J is a Y-chromosome DNA haplogroup. It is one of the major male lines of all living men...
.