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Tyrosinase-negative oculocutaneous albinism(OCA1A)

MedGen UID:
1643910
Concept ID:
C4551504
Disease or Syndrome
Synonyms: Albinism, oculocutaneous, type IA; OCA1A; Oculocutaneous albinism type 1A
SNOMED CT: Tyrosinase-negative oculocutaneous albinism (6483008); OCA1 - Tyrosinase-negative oculocutaneous albinism (6483008); Tyrosinase-related oculocutaneous albinism (6483008)
Modes of inheritance:
Autosomal recessive inheritance
MedGen UID:
141025
Concept ID:
C0441748
Intellectual Product
Source: Orphanet
A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele).
 
Gene (location): TYR (11q14.3)
 
Monarch Initiative: MONDO:0008745
OMIM®: 203100
Orphanet: ORPHA79431

Definition

Researchers have identified multiple types of oculocutaneous albinism, which are distinguished by their specific skin, hair, and eye color changes and by their genetic cause. Oculocutaneous albinism type 1 is characterized by white hair, very pale skin, and light-colored irises. Type 2 is typically less severe than type 1; the skin is usually a creamy white color and hair may be light yellow, blond, or light brown. Type 3 includes a form of albinism called rufous oculocutaneous albinism, which usually affects dark-skinned people. Affected individuals have reddish-brown skin, ginger or red hair, and hazel or brown irises. Type 3 is often associated with milder vision abnormalities than the other forms of oculocutaneous albinism. Type 4 has signs and symptoms similar to those seen with type 2.

Oculocutaneous albinism is a group of conditions that affect coloring (pigmentation) of the skin, hair, and eyes. Affected individuals typically have very fair skin and white or light-colored hair. Long-term sun exposure greatly increases the risk of skin damage and skin cancers, including an aggressive form of skin cancer called melanoma, in people with this condition. Oculocutaneous albinism also reduces pigmentation of the colored part of the eye (the iris) and the light-sensitive tissue at the back of the eye (the retina). People with this condition usually have vision problems such as reduced sharpness; rapid, involuntary eye movements (nystagmus); and increased sensitivity to light (photophobia).

Several additional types of this disorder have been proposed, each affecting one or a few families. [from MedlinePlus Genetics]

Clinical features

From HPO
Photophobia
MedGen UID:
43220
Concept ID:
C0085636
Sign or Symptom
Excessive sensitivity to light with the sensation of discomfort or pain in the eyes due to exposure to bright light.
Albinism
MedGen UID:
182
Concept ID:
C0001916
Disease or Syndrome
An abnormal reduction in the amount of pigmentation (reduced or absent) of skin, hair and eye (iris and retina).
White hair
MedGen UID:
66797
Concept ID:
C0239804
Finding
Hypopigmented hair that appears white.
Absent skin pigmentation
MedGen UID:
393051
Concept ID:
C2673954
Finding
Lack of skin pigmentation (coloring).
Hypopigmentation of hair
MedGen UID:
480031
Concept ID:
C3278401
Finding
Astigmatism
MedGen UID:
2473
Concept ID:
C0004106
Disease or Syndrome
Astigmatism (from the Greek 'a' meaning absence and 'stigma' meaning point) is a condition in which the parallel rays of light entering the eye through the refractive media are not focused on a single point. Both corneal and noncorneal factors contribute to refractive astigmatism. Corneal astigmatism is mainly the result of an aspheric anterior surface of the cornea, which can be measured readily by means of a keratometer; in a small fraction of cases (approximately 1 in 10) the effect is neutralized by the back surface. The curvature of the back surface of the cornea is not considered in most studies, because it is more difficult to measure; moreover, in the case of severe corneal astigmatism, there is evidence that both surfaces have the same configuration. Noncorneal factors are errors in the curvature of the 2 surfaces of the crystalline lens, irregularity in the refractive index of the lens, and an eccentric lens position. Since the cornea is the dominant component of the eye's refracting system, a highly astigmatic cornea is likely to result in a similarly astigmatic ocular refraction (summary by Clementi et al., 1998).
Exotropia
MedGen UID:
4613
Concept ID:
C0015310
Disease or Syndrome
A form of strabismus with one or both eyes deviated outward.
Myopia
MedGen UID:
44558
Concept ID:
C0027092
Disease or Syndrome
Nearsightedness, also known as myopia, is an eye condition that causes blurry distance vision. People who are nearsighted have more trouble seeing things that are far away (such as when driving) than things that are close up (such as when reading or using a computer). If it is not treated with corrective lenses or surgery, nearsightedness can lead to squinting, eyestrain, headaches, and significant visual impairment.\n\nNearsightedness usually begins in childhood or adolescence. It tends to worsen with age until adulthood, when it may stop getting worse (stabilize). In some people, nearsightedness improves in later adulthood.\n\nFor normal vision, light passes through the clear cornea at the front of the eye and is focused by the lens onto the surface of the retina, which is the lining of the back of the eye that contains light-sensing cells. People who are nearsighted typically have eyeballs that are too long from front to back. As a result, light entering the eye is focused too far forward, in front of the retina instead of on its surface. It is this change that causes distant objects to appear blurry. The longer the eyeball is, the farther forward light rays will be focused and the more severely nearsighted a person will be.\n\nNearsightedness is measured by how powerful a lens must be to correct it. The standard unit of lens power is called a diopter. Negative (minus) powered lenses are used to correct nearsightedness. The more severe a person's nearsightedness, the larger the number of diopters required for correction. In an individual with nearsightedness, one eye may be more nearsighted than the other.\n\nEye doctors often refer to nearsightedness less than -5 or -6 diopters as "common myopia." Nearsightedness of -6 diopters or more is commonly called "high myopia." This distinction is important because high myopia increases a person's risk of developing other eye problems that can lead to permanent vision loss or blindness. These problems include tearing and detachment of the retina, clouding of the lens (cataract), and an eye disease called glaucoma that is usually related to increased pressure within the eye. The risk of these other eye problems increases with the severity of the nearsightedness. The term "pathological myopia" is used to describe cases in which high myopia leads to tissue damage within the eye.
Nystagmus
MedGen UID:
45166
Concept ID:
C0028738
Disease or Syndrome
Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms.
Strabismus
MedGen UID:
21337
Concept ID:
C0038379
Disease or Syndrome
A misalignment of the eyes so that the visual axes deviate from bifoveal fixation. The classification of strabismus may be based on a number of features including the relative position of the eyes, whether the deviation is latent or manifest, intermittent or constant, concomitant or otherwise and according to the age of onset and the relevance of any associated refractive error.
Ocular albinism
MedGen UID:
38147
Concept ID:
C0078917
Congenital Abnormality
An abnormal reduction in the amount of pigmentation (reduced or absent) of the iris and retina.
Reduced visual acuity
MedGen UID:
65889
Concept ID:
C0234632
Finding
Diminished clarity of vision.
Blue irides
MedGen UID:
108297
Concept ID:
C0578626
Finding
A markedly blue coloration of the iris.
Hypoplasia of the fovea
MedGen UID:
393047
Concept ID:
C2673946
Finding
Underdevelopment of the fovea centralis.
Visual impairment
MedGen UID:
777085
Concept ID:
C3665347
Finding
Visual impairment (or vision impairment) is vision loss (of a person) to such a degree as to qualify as an additional support need through a significant limitation of visual capability resulting from either disease, trauma, or congenital or degenerative conditions that cannot be corrected by conventional means, such as refractive correction, medication, or surgery.
Abnormality of refraction
MedGen UID:
871349
Concept ID:
C4025843
Anatomical Abnormality
An abnormality in the process of focusing of light by the eye in order to produce a sharp image on the retina.

Professional guidelines

PubMed

Shimizu H
Acta Derm Venereol 1997 Jan;77(1):10-3. doi: 10.2340/0001555577010013. PMID: 9059668
Shimizu H
Keio J Med 1996 Mar;45(1):28-36. doi: 10.2302/kjm.45.28. PMID: 8882465
Shimizu H, Niizeki H, Suzumori K, Aozaki R, Kawaguchi R, Hikiji K, Nishikawa T
J Invest Dermatol 1994 Jul;103(1):104-6. doi: 10.1111/1523-1747.ep12391833. PMID: 8027570

Recent clinical studies

Etiology

Shimizu H, Niizeki H, Suzumori K, Aozaki R, Kawaguchi R, Hikiji K, Nishikawa T
J Invest Dermatol 1994 Jul;103(1):104-6. doi: 10.1111/1523-1747.ep12391833. PMID: 8027570
Tomita Y
J Invest Dermatol 1993 Feb;100(2 Suppl):186S-190S. PMID: 8433007
Clarke DJ, Buckley ME
Br J Psychiatry 1989 Oct;155:551-3. doi: 10.1192/bjp.155.4.551. PMID: 2611578
Westerhof W, Pavel S, Kammeyer A, Beusenberg FD, Cormane R
J Invest Dermatol 1987 Jul;89(1):78-81. doi: 10.1111/1523-1747.ep12580422. PMID: 3598203

Diagnosis

Shimizu H
Acta Derm Venereol 1997 Jan;77(1):10-3. doi: 10.2340/0001555577010013. PMID: 9059668
Shimizu H
Keio J Med 1996 Mar;45(1):28-36. doi: 10.2302/kjm.45.28. PMID: 8882465
Falik-Borenstein TC, Holmes SA, Borochowitz Z, Levin A, Rosenmann A, Spritz RA
Prenat Diagn 1995 Apr;15(4):345-9. doi: 10.1002/pd.1970150408. PMID: 7617575
Shimizu H, Niizeki H, Suzumori K, Aozaki R, Kawaguchi R, Hikiji K, Nishikawa T
J Invest Dermatol 1994 Jul;103(1):104-6. doi: 10.1111/1523-1747.ep12391833. PMID: 8027570
Tomita Y
J Invest Dermatol 1993 Feb;100(2 Suppl):186S-190S. PMID: 8433007

Therapy

White CP, Waldron M, Jan JE, Carter JE
Am J Med Genet 1993 Jun 15;46(5):592-6. doi: 10.1002/ajmg.1320460526. PMID: 8322826

Prognosis

Park KC, Chintamaneni CD, Halaban R, Witkop CJ Jr, Kwon BS
Am J Hum Genet 1993 Feb;52(2):406-13. PMID: 8430701Free PMC Article
Clarke DJ, Buckley ME
Br J Psychiatry 1989 Oct;155:551-3. doi: 10.1192/bjp.155.4.551. PMID: 2611578

Clinical prediction guides

Matsunaga J, Dakeishi M, Shimizu H, Tomita Y
J Dermatol Sci 1996 Nov;13(2):134-9. doi: 10.1016/s0923-1811(96)00519-1. PMID: 8953413
Park KC, Chintamaneni CD, Halaban R, Witkop CJ Jr, Kwon BS
Am J Hum Genet 1993 Feb;52(2):406-13. PMID: 8430701Free PMC Article
Giebel LB, Strunk KM, King RA, Hanifin JM, Spritz RA
Proc Natl Acad Sci U S A 1990 May;87(9):3255-8. doi: 10.1073/pnas.87.9.3255. PMID: 1970634Free PMC Article

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