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In humans, there are two principal types of albinism: oculocutaneous, affecting the eyes, skin and hair, and ocular affecting the eyes only.
There are different types of oculocutaneous albinism depending on which gene has undergone mutation. With some there is no pigment at all. The other end of the spectrum of albinism is "a form of albinism called rufous oculocutaneous albinism, which usually affects dark-skinned people".
According to the National Organization for Albinism and Hypopigmentation, "With ocular albinism, the color of the iris of the eye may vary from blue to green or even brown, and sometimes darkens with age. However, when an eye doctor examines the eye by shining a light from the side of the eye, the light shines back through the iris since very little pigment is present."
Because individuals with albinism have skin that entirely lacks the dark pigment melanin, which helps protect the skin from the sun's ultraviolet radiation, their skin can burn more easily from overexposure.
The human eye normally produces enough pigment to color the iris blue, green or brown and lend opacity to the eye. In photographs, those with albinism are more likely to demonstrate "red eye", due to the red of retina being visible through the iris. Lack of pigment in the eyes also results in problems with vision, both related and unrelated to photosensitivity.
Those afflicted with albinism are generally as healthy as the rest of the population (but see related disorders below), with growth and development occurring as normal, and albinism by itself does not cause mortality, although the lack of pigment blocking ultraviolet radiation increases the risk of melanomas (skin cancers) and other problems.
Development of the optical system is highly dependent on the presence of melanin. For this reason, the reduction or absence of this pigment in people with albinism may lead to:
- Misrouting of the retinogeniculate projections, resulting in abnormal decussation (crossing) of optic nerve fibres
- Photophobia and decreased visual acuity due to light scattering within the eye (ocular straylight) Photophobia is specifically when light enters the eye, unrestricted—with full force. It is painful and causes extreme sensitivity to light.
- Reduced visual acuity due to foveal hypoplasia and possibly light-induced retinal damage.
Eye conditions common in albinism include:
- Nystagmus, irregular rapid movement of the eyes back and forth, or in circular motion.
- Amblyopia, decrease in acuity of one or both eyes due to poor transmission to the brain, often due to other conditions such as strabismus.
- Optic nerve hypoplasia, underdevelopment of the optic nerve.
The improper development of the retinal pigment epithelium (RPE), which in normal eyes absorbs most of the reflected sunlight, further increases glare due to light scattering within the eye. The resulting sensitivity (photophobia) generally leads to discomfort in bright light, but this can be reduced by the use of sunglasses or brimmed hats.
Ocular albinism is a form of albinism which, in contrast to oculocutaneous albinism, presents primarily in the eyes. There are multiple forms of ocular albinism, which are clinically similar.
Both known genes are on the X chromosome. When the term ""autosomal recessive ocular albinism"" ("AROA") is used, it usually refers to mild variants of oculocutaneous albinism rather than ocular albinism, which is "X-linked".
Oculocutaneous albinism (OCA) is a form of albinism involving the eyes (""), the skin ("-"), and according to some definitions, the hair.
Overall, an estimated 1 in 20,000 people worldwide are born with oculocutaneous albinism. OCA is caused by mutations in several genes that control the synthesis of melanin within the melanocytes.
Four types of oculocutaneous albinism have been described, all caused by a disruption of melanin synthesis and all autosomal recessive disorders.
People with CHS have light skin and silvery hair (albinism) and frequently complain of solar sensitivity and photophobia. Other signs and symptoms vary considerably, but frequent infections and neuropathy are common. The infections involve mucous membranes, skin, and the respiratory tract. Affected children are susceptible to infection by Gram-positive and gram-negative bacteria and fungi, with "Staphylococcus aureus" being the most common infection cause. Infections in CHS patients tend to be very serious and even life-threatening. Neuropathy often begins in the teenage years and becomes the most prominent problem. Few patients with this condition live to adulthood.
Most children with Chédiak–Higashi syndrome ultimately reach a stage known as the "accelerated phase", or the "lymphoma-like syndrome", in which defective white blood cells divide uncontrollably and invade many of the body's organs. The accelerated phase is associated with fever, episodes of abnormal bleeding, overwhelming infections, and organ failure. These medical problems are usually life-threatening in childhood.
The precise symptoms of a primary immunodeficiency depend on the type of defect. Generally, the symptoms and signs that lead to the diagnosis of an immunodeficiency include recurrent or persistent infections or developmental delay as a result of infection. Particular organ problems (e.g. diseases involving the skin, heart, facial development and skeletal system) may be present in certain conditions. Others predispose to autoimmune disease, where the immune system attacks the body's own tissues, or tumours (sometimes specific forms of cancer, such as lymphoma). The nature of the infections, as well as the additional features, may provide clues as to the exact nature of the immune defect.
There are several manifestations of Chédiak–Higashi syndrome as mentioned above; however, neutropenia seems to be the most common. The syndrome is associated with oculocutaneous albinism. Persons are prone for infections, especially with "Staphylococcus aureus", as well as "Streptococci".
It is associated with periodontal disease of the deciduous dentition. Associated features include abnormalities in melanocytes (albinism), nerve defects, bleeding disorders.
All types of Griscelli syndrome have distinctive skin and hair coloring.
Type 1 is associated with eurological abnormalities. These include delayed development, intellectual disability, seizures, hypotonia and eye abnormalities.
Type 2 - unlike type 1 - is not associated primary neurological disease but is associated with an uncontrolled T lymphocyte expansion and macrophage activation syndrome. It is often associated with the hemophagocytic syndrome. This latter condition may be fatal in the absence of bone marrow transplantation.
Persons with type 3 have the typical light skin and hair coloring but are otherwise normal.
A number of syndromes escape formal classification but are otherwise recognisable by particular clinical or immunological features.
1. Wiskott–Aldrich syndrome
2. DNA repair defects not causing isolated SCID: ataxia-telangiectasia, ataxia-like syndrome, Nijmegen breakage syndrome, Bloom syndrome
3. DiGeorge syndrome (when associated with thymic defects)
4. Various immuno-osseous dysplasias (abnormal development of the skeleton with immune problems): cartilage–hair hypoplasia, Schimke syndrome
5. Hermansky–Pudlak syndrome type 2
6. Hyper-IgE syndrome
7. Chronic mucocutaneous candidiasis
8. Hepatic venoocclusive disease with immunodeficiency (VODI)
9. XL-dyskeratosis congenita (Hoyeraal-Hreidarsson syndrome)
Griscelli syndrome is defined by the characteristic hypopigmentation, with frequent pyogenic infection, enlargement of the liver and spleen, a low blood neutrophil level, low blood platelet level, and immunodeficiency. Very often there is also impaired natural killer cell activity, absent delayed-type hypersensitivity and a poor cell proliferation response to antigenic challenge. This may be caused by the loss of three different genes, each of which has different additional effects, resulting in three types of syndrome. Its inheritance is autosomal recessive.
Examination of the hair in this syndrome may be useful. Under light microscopy, these hairs exhibit bigger and irregular melanin granules, distributed mainly near the medulla. Under polarized light microscopy, the hairs appear monotonously white.
In addition to HHS-specific sequelae, HHS patients frequently present with the mucocutaneous triad of nail dysplasia, lacy skin pigmentation, and oral leukoplakia
Piebaldism is a rare autosomal dominant disorder of melanocyte development. Common characteristics include a congenital white forelock, scattered normal pigmented and hypopigmented macules 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 and Hirschsprung's disease. It has been documented to occur in all races; early photographers captured many images of African piebalds used as a form of amusement, and George Catlin is believed to have painted several portraits of Native Americans of the Mandan tribe who were affected by piebaldism. Piebaldism is found in nearly every species of mammal. It 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 completely unrelated to acquired or infectious conditions such as vitiligo or poliosis.
"Pie" is a word for multi-colored and "bald" is related to a root word for "skin." Although piebaldism may visually appear to be partial albinism, 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, 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.
The currently recognized features of HHS are cerebellar hypoplasia, immunodeficiency, progressive bone marrow failure, and intrauterine growth retardation. HHS patients also commonly exhibit symptoms such as microcephaly, aplastic anemia, and mental retardation.
In the beginning, medical officials defined ABCD syndrome by the four key characteristics of the syndrome. In the first case study of the Kurdish girl, researches described her as having "albinism and a black lock at the right temporo-occipital region along Blaschko lines, her eyelashes and brows were white, the irises in her eyes appeared to be blue, she had spots of retinal depigmentation, and she did not react to noise." The albinism is interesting in this diagnosis because the skin of an affected individual is albino pale besides the brown patches of mispigmented skin. The "black locks" described and seen in clinical pictures of the infants are thick patches of black hair above the ears that form a half circle reaching to the other ear to make a crest shape.
As identified in this first case study and stated in a dictionary of dermatologic syndromes, ABCD syndrome has many notable features, including "snow white hair in patches, distinct black locks of hair, skin white except brown macules, deafness, irises gray to blue, nystagmus, photophobia, poor visual activity, normal melanocytes in pigmented hair and skin, and absent melanocytes in areas of leukoderma." Individuals have the blue/gray irises typical of people affected by blindness. The C of ABCD syndrome is what distinguishes this genetic disorder from BADS and it involves cell migration disorder of the neurocytes of the gut. This characteristic occurs when nerve cells do not function correctly in the gut, which results in aganglionosis: The intestines’ failure to move food along the digestive tract. Deafness or being unresponsive to noise due to very low quality of hearing was reported in every case of ABCD syndrome. The characteristics of ABCD syndrome are clearly evident in an inflicted individual.
No longer considered a separate syndrome, ABCD syndrome is today considered to be a variation of Shah-Waardenburg type IV. Waardenburg syndrome (WS) is described as "the combination of sensorineural hearing loss, hypopigmentation of skin and hair, and pigmentary disturbances of the irides." Hearing loss and deafness, skin mispigmentation and albinism, and pigmentary changes in irises are the similarities between WS and ABCD. According to a dictionary of dermatologic syndromes, Waardenburg syndrome has many notable features, including "depigmentation of hair and skin – white forelock and premature graying of hair, confluent thick eyebrows, heterochromic irides or hypopigmentation of iris, laterally displaced inner canthi, congenital sensorineural deafness, broad nasal root, autosomal dominant disorder, and other associated findings, including black forelocks."
Griscelli syndrome is a rare autosomal recessive disorder characterized by albinism (hypopigmentation) with immunodeficiency, that usually causes death by early childhood.
This condition causes severe infections. it is characterized by elevated immunoglobulins that function poorly.
Other symptoms are:
- Bronchiectasis
- Hepatosplenomegaly
- Pyoderma
- Emphysema
- Diarrhea
There are a large number of immunodeficiency syndromes that present clinical and laboratory characteristics of autoimmunity. The decreased ability of the immune system to clear infections in these patients may be responsible for causing autoimmunity through perpetual immune system activation.
One example is common variable immunodeficiency (CVID) where multiple autoimmune diseases are seen, e.g., inflammatory bowel disease, autoimmune thrombocytopenia and autoimmune thyroid disease.
Familial hemophagocytic lymphohistiocytosis, an autosomal recessive primary immunodeficiency, is another example. Pancytopenia, rashes, lymphadenopathy and hepatosplenomegaly are commonly seen in these patients. Presence of multiple uncleared viral infections due to lack of perforin are thought to be responsible.
In addition to chronic and/or recurrent infections many autoimmune diseases including arthritis, autoimmune hemolytic anemia, scleroderma and type 1 diabetes are also seen in X-linked agammaglobulinemia (XLA).
Recurrent bacterial and fungal infections and chronic inflammation of the gut and lungs are seen in chronic granulomatous disease (CGD) as well. CGD is caused by a decreased production of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase by neutrophils.
Hypomorphic RAG mutations are seen in patients with midline granulomatous disease; an autoimmune disorder that is commonly seen in patients with granulomatosis with polyangiitis (Wegner’s disease) and NK/T cell lymphomas.
Wiskott-Aldrich syndrome (WAS) patients also present with eczema, autoimmune manifestations, recurrent bacterial infections and lymphoma.
In autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) also autoimmunity and infections coexist: organ-specific autoimmune manifestations (e.g., hypoparathyroidism and adrenocortical failure) and chronic mucocutaneous candidiasis.
Finally, IgA deficiency is also sometimes associated with the development of autoimmune and atopic phenomena.
In reality, immunodeficiency often affects multiple components, with notable examples including severe combined immunodeficiency (which is primary) and acquired immune deficiency syndrome (which is secondary).
The main symptoms of ADA deficiency are pneumonia, chronic diarrhea, and widespread skin rashes. Affected children also grow much more slowly than healthy children and some have developmental delay. Most individuals with ADA deficiency are diagnosed with SCID in the first 6 months of life.
WHIM Syndrome (or Warts, Hypogammaglobulinemia, Immunodeficiency, and Myelokathexis syndrome) is a rare congenital immunodeficiency disorder characterized by chronic noncyclic neutropenia.
Adenosine deaminase deficiency (also called ADA deficiency or ADA-SCID) is an autosomal recessive metabolic disorder that causes immunodeficiency. It occurs in fewer than one in 100,000 live births worldwide.
It accounts for about 15% of all cases of severe combined immunodeficiency (SCID).
ADA deficiency may be present in infancy, childhood, adolescence, or adulthood. Age of onset and severity is related to some 29 known genotypes associated with the disorder.
Griscelli syndrome type 2 (also known as "partial albinism with immunodeficiency") is a rare autosomal recessive syndrome characterized by variable pigmentary dilution, hair with silvery metallic sheen, frequent pyogenic infections, neutropenia, and thrombocytopenia.
HIES often appears early in life with recurrent staphylococcal and candidal infections, pneumonias, and eczematoid skin.
- Autosomal dominant Hyper-IgE Syndrome caused by STAT3 defects, called Job Syndrome, have characteristic facial, dental, and skeletal abnormalities. Patients with STAT3 HIES may have either delay of or failure in shedding of primary teeth. The characteristic facial features are usually set by age 16. These include facial asymmetry, a prominent forehead, deep-set eyes, a broad nasal bridge, a wide, fleshy nasal tip, and mild prognathism. Additionally, facial skin is rough with prominent pores. Finally, some patients with STAT3 HIES have scoliosis, as well as bones that fracture easily.
- Autosomal recessive
Oculocutaneous Albinism Type I or –Type 1A (OCA1A) is an autosomal recessive skin disease associated with albinism. This type of albinism is caused when the gene OCA1 does not function properly.
The location of OCA1 may be written as "11q1.4-q2.1", meaning it is on chromosome 11, long arm, somewhere in the range of band 1, sub-band 4, and band 2, sub-band 1.
ABCD syndrome is defined as albinism, black lock, cell migration disorder of the neurocytes of the gut, and deafness. It was initially misdiagnosed and later discovered that a homozygous mutation in the EDNRB gene causes ABCD syndrome. This helped scientists discover that it is the same as type IV Waardenburg syndrome, also known as Shah-Waardenburg syndrome.