such as "Introduction", "Conclusion"..etc
October 21, 2004 -- Forensic genetics is the branch of genetics that, through DNA analysis
and comparison, deals with the resolution of legal problems such as
paternity tests. Recently, it has been proposed that single nucleotide
polymorphisms (SNPs) could be used as a new genetic marker in the field
eventually even replacing the methods/markers now employed. But in an
article just published online in Forensic Science International, a team
of scientists challenges the effectiveness of SNPs in kinship studies
predicting an increase in inconclusive cases when these markers are
forensic genetics, DNA samples are analysed through the comparison of
particular DNA sequences unique to each individual. In fact, although
more than 99% of the genome is the same across the human population,
variations in DNA sequence called polymorphisms can be used to both
differentiate and correlate individuals.
Short Tandem Repeats (STRs) are the genetic
markers most commonly used in this moment by forensic scientists. STRs
consist of repetitive segments of DNA two to five nucleotides (DNA
building blocks) length found throughout the genome with different
individuals having different STRs combinations.
however, another type of genetic marker called SPNs (single nucleotide
polymorphisms), which consists in DNA sequence variations that result
from alterations in a single nucleotide in the genome sequence, has
been considered to replace STRs in forensic investigations. SNPs seem
to have several advantages over STRs as not only they are a more stable
genetic marker and so are less likely to be lost across generations
which is crucial in paternity cases, but they are also cheaper, easier
and faster to examine and need much smaller DNA samples.
Antonio Amorim and Luisa Pereira at IPATIMUP (Institute of Pathology
and Molecular Immunology, Porto University, Portugal) and the Faculty
of Sciences of the same university show that SNPs analysis can also
have some problems. In fact, the two scientists used statistic
simulations to compare STRs and SNPs effectiveness in kinship studies
and reached the unexpected conclusion that the possibility of
inconclusive results is much higher when using SNPs. Amorim and
Pereira's work question the validity of SNP polymorphisms sole use in
routine paternity investigations and raise the need for a proper
assessment of this technique before any decisions are make.
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