Yes, DNA can be extracted from hair.
Hair can provide DNA for analysis from two main sources: the hair follicle and the hair shaft itself. The presence and quality of DNA, however, vary between these two parts.
DNA Sources in Hair
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Hair Follicle: The hair follicle, the root-like structure at the base of the hair, is a rich source of DNA. If a hair is forcibly removed (pulled out), the follicle often remains attached. This follicle contains cells with nuclei, which house nuclear DNA. It also contains mitochondrial DNA (mtDNA).
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Hair Shaft: The hair shaft, the visible part of the hair, primarily contains keratin, a protein. The hair shaft usually contains mtDNA, which is more abundant and resilient than nuclear DNA. However, the amount of nuclear DNA in the hair shaft is typically very low and can be degraded, making it more difficult to analyze.
Types of DNA Recovered
- Nuclear DNA: Found in the nucleus of cells, nuclear DNA provides a unique genetic profile, useful for individual identification. It's most reliably obtained from the hair follicle.
- Mitochondrial DNA (mtDNA): Found in the mitochondria of cells, mtDNA is inherited maternally. While it doesn't provide as unique a profile as nuclear DNA, it's more abundant and can often be recovered from the hair shaft when nuclear DNA is degraded or unavailable. It is useful for excluding individuals or identifying maternal lineages.
Factors Affecting DNA Recovery
The success of DNA extraction from hair depends on several factors:
- Hair Condition: Damaged or degraded hair may yield less DNA.
- Hair Treatment: Chemical treatments like bleaching or dyeing can degrade DNA.
- Storage Conditions: Heat, humidity, and sunlight can damage DNA.
- Presence of the Follicle: Hairs that have naturally fallen out (telogen hairs) typically lack a follicle and thus may not provide nuclear DNA, although mtDNA might still be recoverable.
Applications
DNA extracted from hair is used in various applications:
- Forensic Science: Identifying suspects or victims in criminal investigations.
- Genetic Genealogy: Tracing family history and ancestry.
- Medical Diagnostics: Identifying genetic predispositions to diseases.
- Paternity Testing: Determining biological parentage.
In conclusion, while DNA can be extracted from hair, the quantity and quality depend on the presence of the hair follicle and the condition of the hair shaft. The hair follicle provides the best source for nuclear DNA analysis, while the hair shaft is primarily used for mitochondrial DNA analysis.
