freckle

Facial freckles on a child.

Freckles are clusters of concentrated melanin which are most often visible on people with a fair complexion. A freckle is also called an "ephelis".

Biology

Freckles can be found on anyone no matter their genetic background; however, having freckles is genetic and is related to the presence of the dominant melanocortin-1 receptor MC1R gene variant.^[1] The formation of freckles is triggered by exposure to sunlight. The exposure to UV-B radiation activates melanocytes to increase melanin production, which can cause freckles to become darker.

Freckles are predominantly found on the face, although they may appear on any skin exposed to the sun, such as the shoulders. Freckles are rare on infants, and more commonly found on children before puberty.

Women with many freckles. Freckles are genetically inherited and related to the presence of the MC1R gene variant.

Upon exposure to the sun, freckles will reappear if they have been altered with creams or lasers and not protected from the sun, but do however fade with age in some cases.

Freckles are not a skin disorder. People with freckles usually have a lower concentration of photoprotective melanin and are therefore more susceptible to the harmful effects of UV-radiation. An overexposure of UV-radiation should be avoided. Sunscreen has been suggested.^{[2] [3]}

Types of freckles

Ephelides is a genetic trait. It is used to describe a freckle which is flat, light brown or red, and fades in the winter. Ephelides are more common in those with light complexions, although they are found on people with a variety of skin tones. The regular use of sunblock can inhibit their development.

Liver spots (also known as sun spots and Lentigines) are freckles that may not fade in the winter. Rather, they form after years of exposure to the sun. Lentigines are more common in older people.

See also

Wikimedia Commons has media related to: Freckles

• Red hair
• Beauty mark
• Mole (skin marking)
• List of Mendelian traits in humans
• Sunscreen

References

• Millington GWM. (2006) Proopiomelanocortin (POMC): the cutaneous roles of its melanocortin products and receptors. Clin Exp Dermatol 31: 407-412.

External links

• MedicineNet.com: Freckles