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What DNA is in Hair?

Published in Hair Genetics 2 mins read

The DNA found in hair is primarily mitochondrial DNA (mtDNA), but it can also contain cellular DNA, depending on the part of the hair being analyzed.

Types of DNA Found in Hair

Hair is composed of two main parts where DNA can be extracted: the hair follicle and the hair shaft. Each of these contains different types and amounts of DNA:

Hair Part DNA Type(s) Amount of DNA
Hair Follicle Cellular DNA and Mitochondrial DNA Higher
Hair Shaft Primarily Mitochondrial DNA (mtDNA) Lower, often very little nuclear DNA

Hair Follicle

The hair follicle, located at the base of the hair, is the most reliable source for DNA. This part of the hair contains:

  • Cellular DNA (Nuclear DNA): This is the genetic material found in the nucleus of cells. It is inherited from both parents, providing a unique genetic profile for an individual.
  • Mitochondrial DNA (mtDNA): This type of DNA is located in the mitochondria of cells. It is inherited only from the mother.

The follicle's higher DNA content allows for more thorough genetic analysis, including nuclear DNA that can be used for individual identification.

Hair Shaft

The hair shaft, which is the visible part of the hair, typically contains:

  • Mitochondrial DNA (mtDNA): The hair shaft typically contains mtDNA due to the presence of mitochondrial remains. This makes it possible to determine maternal lineage.
  • Very little Nuclear DNA: It may also contain a very limited amount of nuclear DNA, but often not in usable quantities for DNA profiling.

Due to the limited amount of DNA, analysis of the hair shaft is more difficult, but mtDNA from the hair shaft has been used successfully in forensic investigations and genealogical research.

Practical Implications

The two sources of DNA in hair serve different purposes:

  • Hair Follicle Analysis: Commonly used in forensic science to identify individuals via cellular DNA, as well as providing mtDNA information.
  • Hair Shaft Analysis: Useful for tracing maternal lineages or ancestry due to the presence of mtDNA, especially when the hair follicle is not available.

In summary, hair contains both cellular and mitochondrial DNA, with the hair follicle containing higher amounts of both and the hair shaft typically containing only mtDNA.