Hair pigmentation


Hair colour is genetically programmed and established in-utero.

Hair colouring relates to the presence or absence of melanin.

Pigmentation is due to the presence of Melanin a water-insoluble polymer of compounds derived from the amino acid Tyrosine which is located within melanocytes.

Melanosynthesis may produce:
Eumelanin – formed by the reaction of the enzyme tyrosinase with the amino acid tyrosine. It produces hair colours varying between reddish brown – black.
Phaeomelanin – formed by the reaction of the enzyme tyrosinase with the amino acids tyrosine and the sulphur rich cysteine. This produces hair colours varying from yellow (blonde) to red (titians).

Variations in pigmentation relate to the number, size and distribution of Melanosomes (single melanin containing organelles) within the Melanocytes. These are specialised skin cells producing melanin and having branches (dentrites) located within hair follicles through which tiny pigment granules are injected into the keratinocytes during hair shaft genesis.

Other considerations:
Melanin affords some skin protection by absorbing ultraviolet radiation.
Tyrosinase inactivity > nil melanogenesis = possible Albinism.

Titian Hair MC1R and pain thresholds
In 2000 scientists identified the gene responsible for titian hair –  MC1R  (Melanocortin 1 Receptor) protein which is involved in skin and hair colour regulation.

Carriers of a mutated version of MC1R have a 1/64 chance of parenting a child with titian hair, pale skin and blue eyes.

It is suggested that MC1R mutation releases a hormone in the brain which mimics endorphins.  Endorphins have several functions one of which provides pain relief. This may affect how the body receives pain signals from the brain.  Consequently red heads may need smaller does of certain pain killing drugs.

© 2000 – B Stevens FTTS