Episode 12.
Melanin Genetics

Question:

Can a baby be born with pink hair?

Key Points:

  • Our natural hair color is controlled by our chromosomes, sometimes called our genes
  • We as humans have 23 pairs of chromosomes, one of each from our mom and one from our dad
  • Mitosis is the process our normal cells take to replicate: the DNA stays exactly the same (hopefully)
  • Meiosis is the process our bodies use to make cells which can be used to make a baby
  • In Meiosis, our chromosomes trade genes back and forth through "crossing over"
  • The result in Meiosis is 4 different cells which all have a different set of 23 chromosomes which collectively have 2 sets of all my genes but each cell has a chromosome that is different than mine
  • Melanin is what gives our body color for everything: skin, eyes, and hair
  • The two main types of melanin (for hair color) are Eumalanin and Pheomelanin
  • Eumelanin comes in two subtypes: black and brown, and Pheomelanin comes in two subtypes: yellow and red
  • Unless something is wrong, people produce the same amount of melanin, the difference is in the ratios of black vs brown, red vs yellow, and eumelanin vs pheomelanin
  • The MC1R gene is the main gene which controls the ratios
  • The OCA2 gene produces a P-protein which seems to somehow impact melanin production, but scientists aren't sure how
  • The ASIP gene modifies the MC1R by limiting the ratio of eumelanin to pheomelanin to a mximum level
  • An albino is someone who cannont produse any melanin, usually because of a genetic mutation
  • If someone has very little Eumelanin, then their hair coloring will either be blonde (if they don't have the red gene at all) or somewhere in the range between yellow and red: i.e. orange
  • The reason hair cannot be a true pink color is because to get to pink blue pigment is needed and we don't have a way to produce blue melanin