Alleles
-- One of the different forms of a gene of DNA sequence that can exist at a
single locus. Alternatively, one of several alternate forms of a gene
occupying a particular location on a chromosome.
Chromosome
-- Is composed of DNA, which itself is composed of four (4) nucleotides:
A (adenine); T (thymine); C (cytosine); and G (guanine).
A ladder-shaped structure occurring in cell nucleus, which transmits
hereditary characteristics.
DNA
-- Deoxyribonucleic Acid.
DYS
-- D = DNA: Y = Chromosome; S = (STR) Single Tandem Repeats;
The DYS numbering scheme (e.g. DYS388, DYS 390) for the Y-STR haplotype loci is
controlled and administered by an international standards body called HUGO,
Human Gene Nomenclature Committee based at the University College, London.
These
results compare individuals to see how closely or distantly they may have shared
a common ancestor. The estimated rate of mutational change is estimated to
be approximately one change per 500 generations for these loci (the locations on
the Y chromosome). Since our test uses 12 different loci, it is reasonable
to expect a change to occur every 40 or so generations; however, these
changes can take place at any time.
Gene
-- The fundamental and functional unit of heredity.
Generation:
Genetics uses 20 years for each generation.
Genetic Distance (GD) - The number of mutations separating two individuals. A measure of how closely two individuals are related.
Haplotype
--
Most
commonly refers to an individual's collection of marker values.
Refers to a single or unique set of chromosomes. A set of closely
linked alleles (genes or DNA polymorphisms) inherited as a unit. Different
combinations of polymorphisms are known as haplotypes.
Haplogroup
-- A collection of closely related haplotypes. Haplogroups are groupings of individuals with the same genetic characteristic
such as restriction enzyme recognition sites or deletions at the same location
on the DNA. A haplogroup is a "Distinct Y chromosomes, defined solely
on the basis of unique mutation events (
_______hg1_hg2_hg3
DYS388_12__14__12
DYS393_13__13__13
DYS392_13__11__11
DYS19__14__14__16
DYS390_24__22__25
DYS391_11__10__11
The
above are modal haplotypes; see Wilson's
study. The HG2 haplogroup is the Nordic group. If your results match
one of the above patterns, or differ in just one marker, we feel some confidence
in classifying your haplogroup. For a list of haplogroups, see Y
Chromosome Consortium [Y chromosome haplogroup tree and nomenclature].
Results
that match HG2 indicate a strong connection with Nordic (Scandinavian)
countries. The HG2 Nordic Haplogroup is one of two Nordic Haplogroups.
This indicates that the family of origin were probably of Viking descent or a
male ancestor was of Viking blood.
Kohanim
Project -- See
the website located at http://www.pbs.org/wgbh/nova/israel/familycohanim.html.
Also as well, see Dr. Michael Hammer above.
Loci -- Plural for Locus.
Locus -- A specific location on a chromosome. Sometimes called a marker.
MH
-- Modal Haplotype = Any person who matches exactly the alleles found to be most
common among the descendants of a person. A person who matches 11 alleles while
being only one off in only one (1) loci, will be considered to be in the
haplogroup, rather than in the family haplotype.
MLE
-- The Most Likely Estimate of when the MRCA between two people lived.
Modal -- The most common value for a marker. (This should not be confused with the average value). The modal value for a marker will vary depending on the haplogroup that an individual belongs to.
Modal haplotype -- A haplotype that has marker values that are at or close to the modal values for the respective haplogroup that the individual belongs to.
Each haplogroup (R1b, E3b, I, etc.) has unique modal values for each marker.
MRCA
-- The Most Recent Common Ancestor between two people. See the expanded
definition at the bottom.
Mutation
-- Small changes during the DNA copying process during transfer from father to
son.
SNP -- Single nucleotide polymorphism. Common DNA sequence variations among individuals. For a variation to be considered a SNP, it must occur in at least 1% of the population.
STR
-- Short Tandem Repeats = A VNTR (see below) in which the repeated sequence is
from one (1) to five (5) base pairs.
Triangulization -- A method of determining the Ancestral Haplotype from the haplotype data of known direct line descendants. In Genetic Genealogy, the process of determining the Y chromosome DNA Ancestral Haplotype of a male ancestor by looking at the allele values of the DYS markers in the haplotypes of the tested individuals in a surname project who descend from that ancestor by focusing specifically on the direct paternal line descendants of two or more known and different sons of the common male ancestor. Unless there is an exact match at all alleles at all DYS markers in the haplotypes of the two different direct male lines of descendants, at least three haplotypes are required to triangulate and deduce the ancestral allele for each marker.
Y-chromosome
-- is passed down from generation to generation only through the male line;
from father to son, father to son, etc.
VNTR
-- Variable Number Tandem Repeats. A defined region of DNA containing
multiple copies of short sequences of bases, which are repeated a number of
times, the number of repeats varying among individuals in the population.
Most
Recent Common Ancestor (MRCA)
MRCA:
(most recent common ancestor): the common ancestor between two people.
MLE: most likely estimate of when the most recent common
ancestor between two people lived. It appears that testing labs are using
a probability of 50% when figuring the MLE rather than a higher percentage such
as 90%.
Heyer
principle:
Y chromosome mutations occur generally once every 500 generations per locus (or
"per marker") with a mutation rate of 0.2%.
Example
of Heyer principle:
Using the Heyer principle, we would expect EACH locus to change 1 digit in 500
generations. If we use a 12 marker test, in 500 (generations) / 12
(markers) = 41.667 generations we would expect to have a change in 1 of the 12
markers by one digit. Thus, two
As
genealogists, we want to know when the MRCA between two people lived. We
know that where all 12 markers match, there is a 50% probability that the MRCA
was no longer than 14.4 generations (288 years), and a 90% probability that the
MRCA was within the last 48 generations. The Most Likely Estimate (MLE)
for a 12/12 match, however, is 14.4 generations (which happens to be the 50%
probability figure; 48 at 90%, 63 generations at 95%). The range for a
12/12 match is 1 to 63 generations.
What
if there is an 11/12 marker match? For an 11/12 match, there is a 50%
probability that the MRCA lived no longer than 36 generations, which is also the
MLE. This translates into 36 x 20 = 720 years. The range for an
11/12 match is 1 to 104 generations (85 generations at 90%, 104 at 95%).
What if
there is a 10/12 match? For a 10/12 match, there is a 50% probability that the
MRCA lived no longer than 61 generations, which is also the MLE. This translates
into 61 x 20 = 1220 years. The range for a 10/12 match is 1 to 145
generations (122 at 90%, 145 at 95% probability).
We
do know that if the results of two people are different by one mutation, that
these people are related. If different by two mutations, probably related.
As we see three or more mutations, the people who may be related are very
distantly related. The concept of MRCA puts the relation back many
generations. (Genetics uses 20 years for each generation.)