2
As well as red hair genes there is also IRF4 which acts as a "dimmer" switch for melanin production. It's been dubbed "the Pierce Brosnan gene".
https://www.dailymail.co.uk/health/a...cientists.html
What are the variants of IRF4?
Asian and African populations are fixed for the ancestral rs12203592*C allele, being monomorphic. In European populations, the rs12203592*T allele is found at around 17% allele frequency. This allele frequency is 40% in Ireland.
What are the IRF4-related phenotypes?
The rs12203592*T allele was statistically and significantly associated with dark hair colour, light eye colour, and decreased ability to tan [2,3,7]. Figure 1 shows the frequency of this phenotype by rs12203592 genotype in 1200 individuals from South-east Queensland. Figure 2, 3 and 4 demonstrate the blue eye and freckling phenotype of IRF4 rs12203592*T/T patients. IRF4 has also been one of the few genes linked to hair greying [8].
https://dermnetnz.org/topics/interfe...factor-4-gene/
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