What Is Paternity Testing And How Is It Done?
Smruti Ranjan Sarangi
A paternity test is conducted to prove paternity, that is, whether a
man is the biological father of another individual. This may be
relevant in view of rights and duties of the father. Similarly, a
maternity test can be carried out. This is less common, because at
least during childbirth, except in the case of a pregnancy involving
embryo transfer or egg donation, it is obvious who the mother is.
This by DNA analysis of the three individuals, although older methods
have included ABO blood group typing, analysis of various other
proteins and enzymes, or using HLA antigens. For the most part however,
DNA has all but taken over all the other forms of testing.
The DNA of an individual is almost exactly the same in each and every
somatic cell. Sexual reproduction brings the DNA of both parents
together randomly to create a unique combination of genetic material in
a new cell, so the genetic material of an individual is derived from
the genetic material of their parents. This genetic material is known
as the nuclear genome of the individual, because it is found in the
nucleus.
Comparing the DNA sequence of an individual to that of another
individual can show if one of them was derived from the other or not.
Specific sequences are usually looked at to see if they were copied
verbatim from one of the individuals genome to the other. If that was
the case, then this proves that the genetic material of one individual
was derived from that of the other (i.e.: one is the parent of the
other). Besides the nuclear DNA in the nucleus, the mitochondria in the
cells also have their own genetic material termed the mitochondrial
genome. Mitochondrial DNA comes only from the mother, without any
shuffling.
Proving a relationship based on comparison of the mitochondrial genome
is much easier than that based on the nuclear genome. However, testing
the mitochondrial genome can only prove if two individuals are related
by common descent through maternal lines only from a common ancestor
and is thus of limited value (for instance, it could not be used to
test for paternity).
Obtaining news that a child either is or isn't one's own is something
that a parent or erstwhile parent can undertake at their own expense,
without necessarily informing anyone either about the test or its
result. However this situation will change when the Human Tissue Act
comes into force in the UK in April 2006. Section 45 states that it
will be an offence to possess any bodily material intending that any
human DNA in the material be analysed without qualifying consent
Tests can also be ordered by courts when proof of paternity is
required.
Non-paternity rates !
Meta-analysis of a wide variety of genetic studies appears to show that
the rates of non-paternity in the general population are on the order
of 4% [1] to over 30%, depending on the social group involved. Many
find these rates surprisingly high.
How is DNA Used in Paternity Testing?
Certain regions of human DNA show variations between people. At each of
these regions a person possesses two genetic types (known as alleles),
one inherited from each parent. By looking at a number of these
variable regions in a person a DNA profile is produced. By comparing
the DNA profiles of the mother and child it is possible to determine
which half of the child's DNA was inherited from its mother (maternal
alleles). The other half must therefore have been inherited from the
child's biological father (paternal alleles). The alleged father's
profile is then examined to determine whether he has the DNA types in
his profile that match the paternal alleles in the child. If the man's
DNA types do not match the child's, he is excluded as the biological
father. If the DNA types match, then he is not excluded as the father.
Smruti Ranjan Sarangi has authored many articles on diversified topics
like Technical, Management, and Humanity. For information on Genetic
Testing, DNA Testing and DNA Paternity Testing. visit
http://www.TestingMaster.com
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