7/30/2019 Albinism m

1/14

Albinism

By

Dr Saad Al Mohizea

7/30/2019 Albinism m

2/14

OCA type 1

OCA type 1A complete absence of pigment in the skin, thehair, and the eyes

(OCA type 1B) moderate pigmentation in these tissues

(OCA type 1TS), ie, temperature sensitive). pigment in hairfollicles of the cooler areas of the body, such as the armsand the legs

All forms of OCA type 1 also present withphotophobia,moderate-to-severe reduced visual acuity, and nystagmus.

The latter two ocular dysfunctions result from a misroutingof the optic fibers from the retina to the visual cortex

7/30/2019 Albinism m

3/14

OCA type 2

does not present with complete absence ofpigment but rather manifests with a minimal-to-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

7/30/2019 Albinism m

4/14

OCA type 3

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. To date, OCA type 3 has only been genetically

confirmed in dark-skinned individuals (of African

heritage).

The ocular presentations are similar to those in

OCA type 1, but they are not as severe.

7/30/2019 Albinism m

5/14

other

OCA type 4 manifests with a phenotype

resembling OCA type 2

OA manifests with ocular depigmentation and iris

translucency. In addition, patients with OA presentwith 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

7/30/2019 Albinism m

6/14

mutations

OCA type 1 results from mutations in the tyrosinase gene, is inheritedas an autosomal recessive trait. The tyrosinase gene encodes anenzyme that initiates the synthesis of melanin using the substratetyrosine. Specifically, tyrosinase hydroxylates tyrosine todihydroxyphenylalanine (DOPA).

OCA type 2 results from mutation in the Pgene 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 membrane-associatedtransporter 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 isunknown

7/30/2019 Albinism m

7/14

DDX

Chediak-Higashi Syndrome (CHS); Hermansky-Pudlak Syndrome(HPS); and Griscelli Syndrome (GS).

HomocystinuriaMenkes Kinky Hair Disease

Phenylketonuria

Other Problems to be Considered:

HistidinemiaMenkes steely hair disease

Tietz syndromePrader-Willi syndromeAngelman syndrome

http://www.emedicine.com/derm/topic704.htmhttp://www.emedicine.com/derm/topic925.htmhttp://www.emedicine.com/derm/topic926.htmhttp://www.emedicine.com/DERM/topic708.htmhttp://www.emedicine.com/DERM/topic715.htmhttp://www.emedicine.com/DERM/topic712.htmhttp://www.emedicine.com/DERM/topic712.htmhttp://www.emedicine.com/DERM/topic715.htmhttp://www.emedicine.com/DERM/topic708.htmhttp://www.emedicine.com/derm/topic926.htmhttp://www.emedicine.com/derm/topic925.htmhttp://www.emedicine.com/derm/topic925.htmhttp://www.emedicine.com/derm/topic925.htmhttp://www.emedicine.com/derm/topic704.htmhttp://www.emedicine.com/derm/topic704.htmhttp://www.emedicine.com/derm/topic704.htm

7/30/2019 Albinism m

8/14

DX

The hair bulb tyrosinase assay has been used to differentiatebetween OCA type 1 and the other forms of albinism. scalp hair bulbsare 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 ofalbinism turn dark during the period.

For CHS, a confirmatory workup consists of analysis of a blood smearand the subsequent identification of neutrophils containing giantcytoplasmic granules.

For HPS, a confirmatory workup consists of electron microscopy ofplatelets and the subsequent identification of the absence of densebodies (delta granules) and bleeding time determination that

demonstrates a prolonged duration. For GS, confirmatory workup consist of immunological function

evaluation plus both CT and MRI for neurological abnormalities.

7/30/2019 Albinism m

9/14

RX

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

7/30/2019 Albinism m

10/14

RX

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

http://162.129.70.33/images/Oculocutaneous_Albinism_1_051003.jpg

7/30/2019 Albinism m

11/14

http://162.129.70.33/images/Oculocutaneous_Albinism_1_051003.jpg

7/30/2019 Albinism m

12/14

7/30/2019 Albinism m

13/14

7/30/2019 Albinism m

14/14