Understanding the mechanism of hair color could be particularly useful to developers of hair color formulations and products, and could even point to new developments in future product conceptions.
The study is said to be the first time that the molecular basis that determines hair coloring has been unraveled, and also outlines tiny DNA changes that can reverberate through the genome, ultimately determining certain characteristics of evolution and migration.
Crucial signaling molecules affect hair color
"We've been trying to track down the genetic and molecular basis of naturally occurring traits — such as hair and skin pigmentation — in fish and humans to get insight into the general principles by which traits evolve," said David Kingsley, PhD, professor of developmental biology.
"Now we find that one of the most crucial signaling molecules in mammalian development also affects hair color."
The research found that blond hair is caused by a single change in the DNA that regulates the expression of a gene that encodes a protein called KITLG, which is known as stem cell factor.
The change in hair color is determined by how much KITLG is expressed in the hair follicles, but does not change how it is expressed in the rest of the body, the scientists noted.
Not quite creating a blond bombshell
“Introducing the change into normally brown-haired laboratory mice yields an animal with a decidedly lighter coat — not quite Norma Jeane to Marilyn Monroe, but significant nonetheless,” a report from Stanford University noted.
The change is accounted for by the fact that a single nucleotide called an adenine is replaced by another called a guanine on human chromosome 12, causing a tiny blip on the biological scale, but one that can be discernable in hair coloring, nevertheless.
"What we're seeing is that this regulatory region exercises exquisite control over where, and how much, KITLG expression occurs," said Kingsley. "In this case, it controls hair color."
"It's clear that this hair color change is occurring through a regulatory mechanism that operates only in the hair. This isn't something that also affects other traits, like intelligence or personality. The change that causes blond hair is, literally, only skin deep."