Gary W. Cole, MD, FAAD
Dr. Cole is board certified in dermatology. He obtained his BA degree in bacteriology, his MA degree in microbiology, and his MD at the University of California, Los Angeles. He trained in dermatology at the University of Oregon, where he completed his residency.
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
In this Article
- Freckles facts
- What are freckles?
- What types of freckles are there?
- What are "liver spots" or "age spots"?
- How do freckles develop?
- How important is heredity with freckles?
- What is the medical meaning of freckles?
- How can freckles be prevented?
- What is the treatment for freckles?
- What is the value of freckles?
- Find a local Dermatologist in your town
How do freckles develop?
Freckles are thought to develop as a result of a combination of genetic tendency (inheritance) and sun exposure. Two people receiving the same sun exposure may not have an equal chance of developing freckles. Natural sunlight and artificial suntanning lights emit ultraviolet (UV) rays. After exposure to ultraviolet rays, the outer layer of the skin (the epidermis) thickens and the pigment-producing cells (the melanocytes) produces the pigment melanin at an increased rate. (This production of melanin may give some protection against future sun exposure.)
Of course, people differ a great deal in their reaction to sunlight. To take an extreme example, there is no pigmentation in the skin of an albino because of a defect in melanin metabolism. On the other hand, people with dark complexions are relatively less sensitive to sun exposure than fair-skinned people. However, people with dark skin are not entirely resistant to the effects of the sun, and they, too, can become sunburned with prolonged exposure. People with blond or red hair, light-colored eyes, and fair skin are especially susceptible to the damaging effect of UV rays.
Freckling is caused by the uneven distribution of the melanin pigment in the skin. A freckle is essentially nothing more than an unusually heavy deposit of melanin at one spot in the skin.
How important is heredity with freckles?
Heredity and skin type are very important factors for the tendency to develop freckles. Freckles tend to be inherited genetically and are most common in individuals with fair skin and/or with blond or red hair.
Research in twin siblings, including pairs of identical twins and pairs of fraternal (nonidentical) twins, have found a striking similarity in the total number of freckles found on each pair of identical twins. Such similarities were considerably less common in fraternal twins. These studies strongly suggest that the occurrence of freckles is influenced by genetic factors. The variations in freckle counts appear to be due largely to heredity.
Ongoing research in a rare disease called xeroderma pigmentosum has also confirmed the genetic tendency of freckles. Excessive freckles in dark-haired individuals are quite common in this disease.
Further, freckles are also found in skin folds like the underarms in another uncommon genetic disease called neurofibromatosis.
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