Albinism Workup

  • Author: Mounir Bashour, MD, CM, FRCS(C), PhD, FACS; Chief Editor: Hampton Roy Sr, MD   more...
 
Updated: Apr 10, 2012
 

Laboratory Studies

  • Hair bulb assays help to indicate the status of tyrosinase activity. Hair bulbs are taken from the scalp, and the catalytic activity of tyrosinase is determined either by incubation in DOPA and consequential induction of melanin determined by visual inspection or by a radioactive biochemical assay in which the samples are incubated with a radiolabeled tyrosine precursor and the amount of radiolabel released after enzymatic conversion quantified spectrophotometrically. The usefulness of this test is debatable because a negative result indicates oculocutaneous albinism (OCA) 1A, but a positive result still leaves the possibility of OCA 1, OCA 2, OCA 3, or OA 1.
  • The most definitive test in determining the albinism type is genetic sequence analysis. Of course, the test is useful only for families with individuals who have albinism. The test cannot be used as a screening tool.
  • Genetic sequence analysis can be used to determine if a fetus has albinism. Amniocentesis at 16-18 weeks could be performed to obtain a sample for analysis. However, parents should be aware that children with albinism could function well and have a good prognosis.
  • Obtain a bleeding time if the patient is planning to undergo surgery. Some physicians believe that a bleeding time should be obtained in all albino persons. If Hermansky-Pudlak syndrome (HPS) is suspected, bleeding time, platelet aggregation, and platelet electron microscopy is necessary.
  • If Chediak-Higashi syndrome (CHS) is suspected, a hematologist should evaluate polymorphonuclear leukocyte function.
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Other Tests

  • Visual-evoked potential tests
    • Sweep visual-evoked potential (VEP) testing can be used as a predictive tool for recognition acuity in children with albinism. Predictability was found in a clinical spectrum of albinism.[7]
    • Pattern-appearance VEP shows a strong association between the magnitude of the interhemispheric latency asymmetry and the clinical signs of albinism.[8]
    • Flash VEP also shows a strong association between the magnitude of the interhemispheric latency asymmetry and the clinical signs of albinism.[8]
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Histologic Findings

Histologic examination of the skin of male patients with this condition and female carriers of OA1 reveals the presence of macromelanosomes.

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Contributor Information and Disclosures
Author

Mounir Bashour, MD, CM, FRCS(C), PhD, FACS  Assistant Professor of Ophthalmology, McGill University; Clinical Assistant Professor of Ophthalmology, Sherbrooke University; Medical Director, Cornea Laser and Lasik MD

Mounir Bashour, MD, CM, FRCS(C), PhD, FACS is a member of the following medical societies: American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus, American College of International Physicians, American College of Surgeons, American Medical Association, American Society of Cataract and Refractive Surgery, American Society of Mechanical Engineers, American Society of Ophthalmic Plastic and Reconstructive Surgery, Biomedical Engineering Society, Canadian Medical Association, Canadian Ophthalmological Society, Contact Lens Association of Ophthalmologists, International College of Surgeons US Section, Ontario Medical Association, Quebec Medical Association, and Royal College of Physicians and Surgeons of Canada

Disclosure: Nothing to disclose.

Coauthor(s)

Khalid Hasanee, MD  Glaucoma and Anterior Segment Fellow, Department of Ophthalmology, University of Toronto

Khalid Hasanee, MD is a member of the following medical societies: Canadian Medical Association, Canadian Ophthalmological Society, and Ontario Medical Association

Disclosure: Nothing to disclose.

Iqbal Ike K Ahmed, MD, FRCSC  Clinical Assistant Professor, Department of Ophthalmology, University of Utah

Iqbal Ike K Ahmed, MD, FRCSC is a member of the following medical societies: American Academy of Ophthalmology, American Society of Cataract and Refractive Surgery, Canadian Ophthalmological Society, and Ontario Medical Association

Disclosure: Nothing to disclose.

Specialty Editor Board

Gerhard W Cibis, MD  Clinical Professor, Director of Pediatric Ophthalmology Service, Department of Ophthalmology, University of Kansas School of Medicine

Gerhard W Cibis, MD is a member of the following medical societies: American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus, and American Ophthalmological Society

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD  Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

J James Rowsey, MD  Former Director of Corneal Services, St Luke's Cataract and Laser Institute

J James Rowsey, MD is a member of the following medical societies: American Academy of Ophthalmology, American Association for the Advancement of Science, American Medical Association, Association for Research in Vision and Ophthalmology, Florida Medical Association, Pan-American Association of Ophthalmology, Sigma Xi, and Southern Medical Association

Disclosure: Nothing to disclose.

Lance L Brown, OD, MD  Ophthalmologist, Affiliated With Freeman Hospital and St John's Hospital, Regional Eye Center, Joplin, Missouri

Disclosure: Nothing to disclose.

Chief Editor

Hampton Roy Sr, MD  Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences

Hampton Roy Sr, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, and Pan-American Association of Ophthalmology

Disclosure: Nothing to disclose.

References

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  2. Schiaffino MV, Tacchetti C. The ocular albinism type 1 (OA1) protein and the evidence for an intracellular signal transduction system involved in melanosome biogenesis. Pigment Cell Res. Aug 2005;18(4):227-33. [Medline].

  3. Innamorati G, Piccirillo R, Bagnato P, Palmisano I, Schiaffino MV. The melanosomal/lysosomal protein OA1 has properties of a G protein-coupled receptor. Pigment Cell Res. Apr 2006;19(2):125-35. [Medline].

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  9. Onojafe IF, Adams DR, Simeonov DR, et al. Nitisinone improves eye and skin pigmentation defects in a mouse model of oculocutaneous albinism. J Clin Invest. Oct 2011;121(10):3914-23. [Medline]. [Full Text].

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  17. Kanski JJ. Albinism. Clin Ophthalmol. 1999;459-461.

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  19. King RA, Pietsch J, Fryer JP, et al. Tyrosinase gene mutations in oculocutaneous albinism 1 (OCA1): definition of the phenotype. Hum Genet. Nov 2003;113(6):502-13. [Medline].

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Table 1. Oculocutaneous Albinism Types
OCA SubtypesGene PositionAffected Protein
OCA 1
  • OCA 1A (tyrosinase-negative OCA)
  • OCA 1B (yellow-mutant/Amish/
  • xanthous, temperature-sensitive)
  • OCA 1A/1B heterozygote
11q14-21Tyrosinase
OCA 2



(tyrosinase-positive OCA, brown OCA)



15q11-13P protein
OCA 39p23Tyrosinase-related protein
Table 2. Ocular Albinism Types
OA SubtypesGene PositionAffected Protein
OA 1 (X-linked recessive OA/Nettleshop-Falls type)X p22.3-22.2The protein product of the OA 1 gene named OA 1 (and also identified as GPR143 in GenBank)[2, 3]
AROANot a distinct positionTyrosinase in some cases;



P protein in some cases



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