Piebaldism refers to the absence of mature melanin-forming cells (melanocytes) in certain areas of the skin and hair. It is a rare

autosomal dominant In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...

disorder of

melanocyte Melanocytes are melanin-producing neural crest-derived cells located in the bottom layer (the stratum basale) of the skin's epidermis, the middle layer of the eye (the uvea), the inner ear, vaginal epithelium, meninges, bones, and heart. ...

development.James, William; Berger, Timothy; Elston, Dirk (2005). ''Andrews' Diseases of the Skin: Clinical Dermatology''. (10th ed.). Saunders. . Common characteristics include a congenital white

forelock The forelock or foretop is a part of a horse's mane, that grows from the animal's poll and falls forward between the ears and onto the forehead. Some breeds, particularly pony breeds, have a naturally thick forelock, while other breeds, such as ...

, scattered normal pigmented and hypopigmented

macule A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, nails, and related muscle and glands. The major function of this s ...

s and a triangular shaped depigmented patch on the forehead. There is nevertheless great variation in the degree and pattern of presentation, even within affected families. In some cases, piebaldism occurs together with severe developmental problems, as in

Waardenburg syndrome Waardenburg syndrome is a group of rare genetic conditions characterised by at least some degree of congenital hearing loss and pigmentation deficiencies, which can include bright blue eyes (or Heterochromia iridum, one blue eye and one brown ey ...

and

Hirschsprung's disease Hirschsprung's disease (HD or HSCR) is a birth defect in which nerves are missing from parts of the intestine. The most prominent symptom is constipation. Other symptoms may include vomiting, abdominal pain, diarrhea and slow growth. Symptoms us ...

. Piebaldism has been documented to occur in all races, and is found in nearly every species of mammal. The condition is very common in mice, rabbits, dogs, sheep, deer, cattle and horses—where selective breeding has increased the incidence of the mutation—but occurs among chimpanzees and other primates only as rarely as among humans. Piebaldism is unrelated to conditions such as

vitiligo Vitiligo is a disorder that causes the skin to lose its color. Specific causes are unknown but studies suggest a link to immune system changes. Signs and symptoms The only sign of vitiligo is the presence of pale patchy areas of depigmen ...

poliosis Poliosis (also called poliosis circumscripta), is the decrease or absence of melanin (or colour) in head hair, eyebrows, eyelashes or any other hairy area. It is popularly known as white forelock when it affects hair directly above the forehead. ...

. Although piebaldism may visually appear to be partial

albinism Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and pink or blue eyes. Individuals with the condition are referred to as albino. Varied use and interpretation of the term ...

, it is a fundamentally different condition. The vision problems associated with albinism are not usually present as eye pigmentation is normal. Piebaldism differs from albinism in that the affected cells maintain the ability to produce pigment but have that specific function turned off. In albinism the cells lack the ability to produce pigment altogether. Human piebaldism has been observed to be associated with a very wide range and varying degrees of endocrine disorders, and is occasionally found together with heterochromia of the irises, congenital deafness, or incomplete gastrointestinal tract development, possibly all with the common cause of premature cutting off of human fetal growth hormone during gestation. Piebaldism is a kind of

neurocristopathy Neurocristopathy is a diverse class of pathologies that may arise from defects in the development of tissues containing cells commonly derived from the embryonic neural crest cell lineage. The term was coined by Robert P. Bolande in 1974. After th ...

, involving defects of various neural crest cell lineages that include melanocytes, but also involving many other tissues derived from the neural crest. Oncogenic factors, including mistranscription, are hypothesized to be related to the degree of phenotypic variation among affected individuals.

Genetics

Piebaldism is an autosomal dominant hereditary condition, which tends to produce high rates of inheritance and long chains of generational transmission. All who inherit the gene have at some time in life evidence of piebald hypopigmentation of the hair or skin, most likely both. Piebaldism may be associated with the genes '' KIT'' or ''

SNAI2 Zinc finger protein SNAI2 is a transcription factor that in humans is encoded by the ''SNAI2'' gene. It promotes the differentiation and migration of certain cells and has roles in initiating gastrulation. Function This gene encodes a member o ...

''.

Diagnosis

Usually diagnosed at birth with the appearance of patches of white skin on the arms, legs, stomach, forehead, and a white lock of hair.

History

Early photographers took many photographs of

African people The population of Africa has grown rapidly over the past century and consequently shows a large youth bulge, further reinforced by a low life expectancy of below 50 years in some African countries. Total population as of 2020 is estimated at ...

with piebaldism as a form of entertainment and exoticism, and

George Catlin George Catlin (July 26, 1796 – December 23, 1872) was an American adventurer, lawyer, painter, author, and traveler, who specialized in portraits of Native Americans in the United States, Native Americans in the Old West. Traveling to the We ...

is believed to have painted several portraits of Native Americans of the

Mandan The Mandan are a Native American tribe of the Great Plains who have lived for centuries primarily in what is now North Dakota. They are enrolled in the Three Affiliated Tribes of the Fort Berthold Reservation. About half of the Mandan still res ...

tribe who were affected by piebaldism. Historically, persons with extensive piebaldism have experienced abuse of the sort still suffered in the present by albinos, especially in Africa. This has ranged from display of unclothed African piebalds in "freak" shows and postcards of the early 20th century to the forcing of piebalds (as in the case of albinos) to work long hours exposed to the sun (producing high rates of lethal skin cancers), to the use of piebald humans, including children, in risky medical experiments. The National Organization of Albinism and Hypopigmentation, as well as organizations such as

Under the Same Sun Under The Same Sun (UTSS) is a Christian charitable organization that promotes the wellbeing of persons with albinism Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and ...

, work to promote awareness of all forms of cutaneous variation and their medical implications, and to highlight human rights issues, especially the plight of albinos subject to extreme persecution in parts of Africa.

Etymology

The word "piebald" originates from a combination of "pie," from "

magpie Magpies are birds of the Corvidae family. Like other members of their family, they are widely considered to be intelligent creatures. The Eurasian magpie, for instance, is thought to rank among the world's most intelligent creatures, and is one ...

", and "bald", meaning "white patch" or spot. The reference is to the distinctive black-and-white plumage of the magpie.

References

External links