Heterochromia is a variation in coloration. The term is most often used to describe color differences of the iris, but can also be applied to color variation of hair or skin.
Here are a few studies related to heterochromia of the hair:
Scalp hair heterochromia involves the presence of two different colors of the scalp hair in the same individual. It may be of three types: patchy, diffuse, and segmental. Isolated patchy heterochromia of the scalp hair is a rare entity, and a very few cases have been described in the literature. Hereby, we report one such case of isolated patchy scalp hair heterochromia in a 2-year-old healthy male child with black hairs presenting with a bunch of blond hairs without any underlying abnormalities along with the literature review.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6984047/
Heterochromia of the hair involves the presence of two distinctive colors of scalp hair in one individual. We report the case of a 4‐year‐old girl with reddish streaks of scalp hair, heterochromia of the eyelashes, and cutaneous hypopigmentation following the lines of Blaschko.
https://onlinelibrary.wiley.com/doi/abs/10.1111/pde.12738
Hair heterochromia involves the presence of two different non-artificially induced colours of hair in the same individual which can be due to either iron deficiency anaemia, genetic mutations or mosaicism. We report a six-month old male infant who presented to the Department of Dermatology, Saham Hospital, Saham, Oman, in 2013 with focal scalp hair heterochromia without any detectable underlying abnormalities. The area of heterochromia was still noticeable at a one-year follow-up.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5380409/
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