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Why Do People Have Birthmarks?

Why Do People Have Birthmarks?


Why do some people have birthmarks while others don’t? There are several factors contributing to the appearance of birthmarks including, ethnicity, genetics, gender, and birth conditions.  Birthmarks can be divided into two main groups, pigmented and vascular.  Pigmented birthmarks occur in 2% of births while more than one in ten babies is born with some kind of vascular birthmark, such as hemangiomas and port wine stains. [American Family Physician] [American Academy of Dermatology]

Gender Specific Birthmarks

Some birthmark types are more prevalent in one gender than another.  For example, infantile hemangiomas, a congenital vascular malformation, are three times more common in females than males. [University of California San Francisco School of Medicine]

Birthmarks Associated with Birthing Conditions

Some birthmarks are more prevalent under certain birth conditions.  For example, hemangiomas are more common in multiple births and in low birth weight premature births. [Cleveland Clinic] Advanced maternal age may also play a factor. [DermNet NZ]

How Does Genetics Factor in Birthmark Incidence Rate?

Though it has been believed that, for the most part, heredity does not play a factor in birthmark formation, researchers have recently discovered that this may not be entirely true.

Bjorn Olsen, Harvard Forsyth Professor of Oral Biology,  has recently discovered a gene which passes on the susceptibility in certain families to develop venous malformations known as vascular birthmarks. Vascular birthmarks, including hemangiomas and stork bites, result because of an overabundance of blood vessels. [Harvard University Gazette]

Neurofibromatosis . Certain birthmarks may indicate underlying conditions. Neurofibromatosis is a condition which occurs in about one in every three-thousand births in the United States and is often signaled by the presence of six or more café au lait spots. Half of neurofibromatosis cases are inherited with the rest occurring because of a genetic mutation. [Yu, Albert C. H]

Klippel-Trenaunay-Weber syndrome . Port wine stains may occur because of Klippel-Trenaunay-Weber syndrome, a genetic mutation that is believed to occur sporadically. Sturge-Weber syndrome is often accompanied with a port wine stain on the forehead and upper eyelid on one side of the face. The causes of this syndrome are unknown. [Genetics Home Reference]

Ethnicity Plays a Major Role in Why Certain People Have Birthmarks

Ethnicity can play a factor in the incidence rate of particular types of birthmarks.

Mongolian blue spots. An example of a birthmark type associated with ethnicity is Mongolian blue spots, also known as Mongolian spots; Congenital dermal melanocytosis; or Dermal melanocytosis. These bluish-gray markings that look almost bruise-like occur primarily in babies of Native American, Asian, and Hispanic descent.  The incident rate for Native Americans has been reported as high as 90%, followed by 80% of Asian descent, and 70% of Hispanic descent. Caucasian babies can also have them but the incidence rate is much lower. (1-10%) [Medscape]

Café au lait birthmarks.  Another example of a birthmark type associated with ethnicity is the café au lait birthmark.  These Café au lait birthmarks are more common in people of African American decent.

In the US, only .3% of Caucasian children are born with this birthmark, while it is present in 18% of African American children.  The number increases into childhood with the birthmark present in 13% of Caucasian children compared to 27% of African American children. [Medscape]

Hemangiomas. Hemangiomas occur most often in babies of Caucasian descent. [Gillette Children’s] For example, salmon patches are present in 44% of infants in the white population. [Consultant for Pediatricians]



“Newborn Skin: Part II. Birthmarks.” – American Family Physician. N.p., n.d. Web. 01 May 2016.

“Different Kinds of Birthmarks.” American Academy of Dermatology. N.p., n.d. Web. 01 May 2016.

“UCSF School of Medicine – Department of Dermatology – Birthmarks and Vascular Anomalies Center.” UCSF School of Medicine – Department of Dermatology – Birthmarks and Vascular Anomalies Center. N.p., n.d. Web. 01 May 2016.

“Birthmarks, Hemangiomas & Port-Wine Stains | Cleveland Clinic.” Birthmarks, Hemangiomas & Port-Wine Stains | Cleveland Clinic. N.p., n.d. Web. 01 May 2016.

Yu, Albert C. H. Gene Expression in the Central Nervous System. Amsterdam: Elsevier, 1995. Print.

“Klippel-Trenaunay Syndrome.” Genetics Home Reference. N.p., n.d. Web. 01 May 2016.

“When a Birthmark Is Born.” The Harvard University Gazette. N.p., n.d. Web. 01 May 2016.

“Congenital Dermal Melanocytosis (Mongolian Spot): Background, Pathophysiology, Epidemiology.” Medscape. N.p., n.d. Web. 01 May 2016.

“Cafe Au Lait Spots: Background, Pathophysiology, Epidemiology.” Medscape. N.p., n.d. Web. 01 May 2016.

“Birthmarks and Skin Anomalies (Nevi, Hemangiomas and Vascular Malformations).” Gillette Children’s Specialty Healthcare. N.p., n.d. Web. 01 May 2016.

Leung AKC, Barankin B. Salmon patches. Consultant for Pediatricians. 2014;13(2):90-92.


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