Phenotype for the Trait
Freckles, also known as ephelides, are a phenotypic characteristic showing skin hyperpigmentation. Freckles are more common in persons with phototypes I and II (fair complexion, blue eyes, blond, redhead) and occur on the parts of the skin that are most exposed to sunlight. Ander, who will be depicted in the assignment, has freckles on his face and back. Non-red hair color predominates over red hair color, and freckles outnumber the usual.
Likely Genotype for the Trait
Denote the gene that causes the development of freckles in a person as K. Then the gene that causes their absence will be denoted as K. Freckles will not occur in people with the genotype kk homozygous for the recessive gene. A person who inherits recessive genes from both parents may have this genotype. The expected genotype of Ander is Kk.
Phenotypes and Genotypes of Biological Family Members
Ander’s mom’s phenotype shows that the woman has red hair and heavily defined freckles all over her body. Ander’s father is a brunette who does not have freckles. Ander’s brother has red hair and a small number of freckles on his face. Mom’s genotype is KK, dad’s is Kk, and brother’s is Kk. Figure 1 shows a probable Punnett square for the Anders family. Based on the data obtained from the study, it can be concluded that (Kk) = 100%.
Other Factors Influencing the Phenotype
Depending on their genes and skin tone, some people are more prone than others to have freckles. No additional patterns of freckle inheritance have been discovered. Exposure to sunlight can cause freckles to emerge if a person is genetically predisposed to them. Freckles are prevalent in youngsters, although they may fade or become less visible as they age.
Freckles occur when melanin, the pigment responsible for skin color, accumulates beneath the skin. Freckles can seem brown, red, or tan. Due to sun exposure and hereditary factors, freckles are more likely in certain persons. Extra melanin is produced by human skin cells to protect the skin from the sun’s rays. This is why freckles emerge after being exposed to sunlight. Freckles can form over a significant skin region and may return or get darker over the summer months. Freckles generally fade or vanish throughout winter when new skin cells replace old skin cells.
The MC1R gene is well-known for its role in creating red hair, albeit this only happens in the MC1R gene variation. When the MC1R gene operates correctly, it produces the melanocortin one receptor protein, which governs the development of eumelanin and pheomelanin, two forms of melanin. Eumelanin protects the skin from the sun’s damaging rays. More pheomelanin is created when the MC1R gene is inhibited from delivering signals to make eumelanin.
An excess of pheomelanin causes red hair and freckles. A team of Icelandic researchers uncovered the significance of IRF4 in the production of freckles just recently. According to the study, a mutation of the IRF4 gene helps prevent the development of an enzyme that drives melanin synthesis, resulting in light pigmentation, freckles, blue eyes, and brown hair (Lucock et al., 2022). This characteristic is widespread in Ireland, Iceland, and throughout Northern Europe.
Although the OCA2 gene has been identified as one of the genetic disorders causing freckles, it is scarce. OCA2, a kind of albinism, causes white hair, very light-colored eyes, and a pale complexion (Walsh & Kayser, 2023). While a total absence of pigmentation distinguishes OCA1, OCA2 is less severe; freckles frequently emerge after sun exposure. Single nucleotide polymorphisms (SNPs) account for much of OCA2’s effect on normal pigmentation. SNPs regulate the degree of OCA2 expression and are linked to increased freckles.
References
Lucock, M. D., Jones, P. R., Veysey, M., Thota, R., Garg, M., Furst, J., Martin, C., Yates, Z., Scarlett, C. J., Jablonski, N. J., Chaplin, C. & Beckett, E. L. (2022). Biophysical evidence to support and extend the vitamin D‐folate hypothesis as a paradigm for the evolution of human skin pigmentation. American Journal of Human Biology, 34(4), e23667. Web.
Walsh, S., & Kayser, M. (2023). Prediction of Physical Characteristics, such as Eye, Hair, and Skin Color, Based Solely on DNA. Forensic DNA Applications: AnInterdisciplinary Perspective, 357.
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