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Albinism is a genetic
disorder which is
characterized by a
defect in the gene
that produces
melanin.
This results in a lack
of pigmentation in
the hair, skin and
eyes (resulting in a
white or pink color).
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OCA type 1A complete absence of pigment in the
skin, the hair, and the eyes
(OCA type 1B) moderate pigmentation in these
tissues
(OCA type 1TS), ie, temperature sensitive). pigment
in hair follicles of the cooler areas of the body,
such as the arms and the legs
All forms of OCA type 1 also present with
photophobia, moderate-to-severe reduced visual
acuity, and nystagmus. The latter two ocular
dysfunctions result from a misrouting of the optic
fibers from the retina to the visual cortex
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does not present with complete absence of
pigment but rather manifests with a minimalto-moderate amount of pigment remaining in
the skin, the hair, and the eyes.
Many patients with OCA type 2 can develop
pigmented freckles, lentigines, and/or nevi
with age.
The ocular presentations are similar to those
in OCA type 1
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manifests with minimal pigment reduction
in the skin, the hair, and the eyes. This form
of albinism was previously referred to as
Rufous albinism and possibly Brown
albinism.
The ocular presentations are similar to
those in OCA type 1, but they are not as
severe.
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OCA type 4 manifests with a phenotype
resembling OCA type 2
OA manifests with ocular depigmentation
and iris translucency. In addition, patients
with OA present with congenital motor
nystagmus that may be accompanied by
reduced visual acuity, refractive errors,
fundus hypopigmentation, lack of foveal
reflex, and strabismus. Cutaneous
depigmentation is not apparent
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Albinism is an autosomal recessive trait.
An individual with albinism must inherit the
albino gene from both of its parents.
This specific type is characterized by
complete lack of tyrosinase activity because
an inactive form of the enzyme is produced.
OCA1A is caused by mutations of the TYR
gene that produce a inactive form of the
tyrosinase enzyme.
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The gene is located on chromosome 11
The lack of this enzyme blocks the first step
of the melanin biosynthetic pathway, and
no melanin is formed in the appropriate
melanocytes.
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OCA type 2 results from mutation in the P gene
OCA type 3 results from mutation in the tyrosinase-related
protein-1 (Tyrp1) gene, is inherited as an autosomal recessive
trait.
OCA type 4 results from mutations in the membraneassociated transporter protein (MATP)
OA results from mutation in a gene on the X chromosome, is
inherited as an X-linked recessive trait. The function of the
OA gene product is unknown
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White or pink hair, skin, eyes
Eye problems: nystagmus (horizontal back and
forth movement of eyes), strabismus (muscle
imbalance, crossed eyes, lazy eye, protruding of
eye), sensitivity to bright light and glare, farsightedness, near-sightedness, astigmatism,
foveal hypoplasia (retina does not develop
normally prenatally or in infancy), nerve signals
from retina to brain do not follow normal nerve
routes, and iris cannot screen out light because of
the lack of pigmentation.
Normal life span, same types of medical problems
as non-albinos.
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The hair bulb tyrosinase assay has been used to differentiate
between OCA type 1 and the other forms of albinism. scalp
hair bulbs are gently plucked from the patient and placed in a
0.1% solution of (L-DOPA) for to 4 hours. If the sample is
from a patient with OCA type 1, the hair bulbs remain white.
In contrast, samples from all other forms of albinism turn
dark during the period.
D/D:
Vitiligo
Piebaldism
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No treatment is available for
hypopigmentation in the skin, the hair, or the
eyes.
The use of broad-spectrum sunscreens and
clothing is recommended to prevent
ultraviolet-induced damage to the skin.
Visual impairment can be improved by using
corrective lenses
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Autosomal dominant inheritence
Melanocytes are absent in affected area
Lesions present at birth
Depigmented macule present symmetrically
with islands of normally pigmented or
hyperpigmented macules withen the area of
depigmented skin
Central parts of face, trunk and proximal
parts of limbs are the common sites
RX:photoprotection,PUVA,Grafting
Chloasma(melasma)
 Etiology:hormonal factors, sunlight
 Females >male
 Age -30-50
 Brown macular pigmentation with well defined
margins, it darkens with exposure to sun
 Common sites:cheeks nose forehead and chin
 RX: photoprotection, combination of topical
hydroquinione,retinoic acid and topical
corticosteroids ,chemical peeling with glycolic
acid or trichloroacetic acid
Freckles
 Autosomal dominant seen in fair individuals
 Normal no. of melanocytes but hyperactive
 Lesions are multiple brown macules which
become darker on sun exposure
 Individual macules may show variation in color
 Face dorsolateral ,aspect of forearm and V of
neck
 RX: photoprotection,topical depigmenting agents
like hydroquinone and azelaicacid, chemopeeling
Lentigines
 Number of melanocytes are increased
 May occur as a part of multisystem syndrome like
Peutz Jegher’s syndrome , etc or occur alone
 Begins in childhood
 Light brown to dark brown uniformly colored
macules appearing at any part of the body
including mucosa irrespective of photo exposure
 RX : not required,facial lesions can be removed
by excision or cryotherapy
Associations:
PeutzJegher’s syndrome:autosomal dominant
 Scattered oral and acral lentigines
 Small intestinal polyps and ovarian tumors
Cronkhite-canada syndrome:
 Multiple lentigines on dors of hands
 Diffuse pigmentation of palms
 Nail abnormalities
 Alopecia
 Intestinal polyposis
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