Markers and Forensic Genetics
Genetic markers:
A genetic marker is some feature in the genome that allows us to
differentiate between different alleles
All markers reflect differences in DNA sequence, but can represent a
variety of types of differences: differences in base composition of
sequence, presence-absence measures.
Most types of markers differ in the technology used to assay them and in
the evolutionary processes shaping variation.
Why do we care?
Markers provide information on genetic differences between individuals
Forensic genetics – match DNA samples to individuals, families or
population of origin e.g. crime scene investigations, paternity tests,
conservation genetics
Complex trait genetics – markers used in QTL and GWAS studies
Measures of genetic diversity – insights into population properties, like
population size which is correlated to allelic diversity.
Not all variation is reflected in markers:
Copy number variation (CNVs): functionally important genetically identical
sequences can be repeated, but be difficult to detect. Estimated that 0.4%
of genome of unrelated individuals shows copy number differences.
Lots of ways to assay markers:
(focus on the examples on the ‘main’ bullet points)
RFLP (restriction fragment length polymorphism)
CAPS (cleaved amplified polymorphic sequences)
SSLP (simple sequence length polymorphism)
- VNTR (variable number of tandem repeats)
- SSR/STR (simple sequence repeats/simple tandem repeats)
SCAR (sequence characterised amplified region)
SNP (single nucleotide polymorphism)
- DASH (dynamic allele-specific hybridisation)
- DNA chip
- DNA sequencing
SSCP (single strand conformation polymorphism)
AFLP (amplified fragment length polymorphism)
RAPD (random amplified polymorphic DNA)
DAF (DNA amplification fingerprinting)
AP-PCR (arbitrarily primed-PCR)
ISSR (inter-simple sequence repeat)
Genetic markers:
A genetic marker is some feature in the genome that allows us to
differentiate between different alleles
All markers reflect differences in DNA sequence, but can represent a
variety of types of differences: differences in base composition of
sequence, presence-absence measures.
Most types of markers differ in the technology used to assay them and in
the evolutionary processes shaping variation.
Why do we care?
Markers provide information on genetic differences between individuals
Forensic genetics – match DNA samples to individuals, families or
population of origin e.g. crime scene investigations, paternity tests,
conservation genetics
Complex trait genetics – markers used in QTL and GWAS studies
Measures of genetic diversity – insights into population properties, like
population size which is correlated to allelic diversity.
Not all variation is reflected in markers:
Copy number variation (CNVs): functionally important genetically identical
sequences can be repeated, but be difficult to detect. Estimated that 0.4%
of genome of unrelated individuals shows copy number differences.
Lots of ways to assay markers:
(focus on the examples on the ‘main’ bullet points)
RFLP (restriction fragment length polymorphism)
CAPS (cleaved amplified polymorphic sequences)
SSLP (simple sequence length polymorphism)
- VNTR (variable number of tandem repeats)
- SSR/STR (simple sequence repeats/simple tandem repeats)
SCAR (sequence characterised amplified region)
SNP (single nucleotide polymorphism)
- DASH (dynamic allele-specific hybridisation)
- DNA chip
- DNA sequencing
SSCP (single strand conformation polymorphism)
AFLP (amplified fragment length polymorphism)
RAPD (random amplified polymorphic DNA)
DAF (DNA amplification fingerprinting)
AP-PCR (arbitrarily primed-PCR)
ISSR (inter-simple sequence repeat)
