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Hair and DNA


DNA Analysis
Only possible if ‘bulb’ at the base of the hair is intact.
The hair bulb forms the base of the hair follicle.
In the hair bulb, living cells divide and grow to build the hair shaft.
Blood vessels nourish the cells in the hair bulb, and deliver hormones that modify hair growth and structure at different times of life.


DNA and Hair Growth Stages
Advancements in DNA profiling can now individualize human hair.
The probability of detecting DNA in hair roots is more likely for hair being examined in its different growth phases.



Anagen- early growth
Catagen- middle
Telogen- final phases


Hair and DNA
When hair is forcibly removed often a follicular tag (a translucent piece of tissue surrounding the hair’s shaft near the root) may be present.

This has proven to be a rich source of nuclear DNA associated with hair.



Hair and Mitochondrial DNA
Mitochondrial DNA is found outside of the nucleus and it is transmitted only from the mother to child.
Mitochondrial DNA can be extracted from the hair shaft.
As a rule, all positive microscopical hair comparisons must be confirmed by DNA analysis.



Hair Collection Baseline
As a general rule, forensic hair comparisons involve either head hair or pubic hair.

Head Hair: 50 full-length head hairs from all areas of the scalp will normally ensure a representative sampling.

Pubic Hair: 24 full-length pubic hairs should cover the range of characteristics present in pubic hair.
Hair samples are also collected from the victims of suspicious deaths during an autopsy.




Link to Lecture Slides: https://drive.google.com/file/d/1-mMA...

*Due to the description character limit the full work cited for "Upper Limbs" can be viewed at... https://drive.google.com/file/d/1R-_X...