OCULOCUTANEOUS ALBINISM TYPE 2

Oculocutaneous Albinism (OCA) is a group of genetically heterogeneous hypopigmentation disorders including OCA1, OCA2, OCA3, and OCA4. All are inherited in an autosomal recessive manner. The most common type of OCA, OCA2, is caused by mutations in the OCA2 gene on chromosome 15. OCA2 is about twice as common as OCA1 in African and African-American populations. It has a prevalence of 1/10,000 among African-Americans and 1/36,000 among Caucasians. Sequence analysis of the entire coding region of the OCA2 gene and deletion analysis of the common 2.7 kb deletion prevalent in patients of African heritage are available on a clinical basis at the Medical Genetics Laboratories at Baylor College of Medicine.

Reasons For Referral:

• Confirmation of clinical diagnosis
• Carrier testing of known familial mutations
• Prenatal Diagnosis (known familial mutations)

Testing Methodology:

PCR amplification of the exons in the entire coding region of the OCA2 gene will be performed on patient genomic DNA. Direct sequencing of amplification products is performed in both the forward and reverse directions using automated fluorescence dideoxy sequencing methods. The common 2.7 kb OCA2 deletion will be analyzed by multiplex PCR.

Specimen Requirements:

Blood: EDTA (purple-top) tubes: Adults: 14 cc; Child: 6 cc; Infant: 2-3 cc
Requisition form must accompany specimen. Prior to any genetic testing, we recommend genetic counseling and request that the subject, or their legal guardian, sign our consent form and submit it with the sample. Please call our laboratory for specific requirements for prenatal testing.

Turnaround Time:

Sequencing Index: 4 weeks
Sequencing Known Familial Mutation: 3 weeks
Targeted Deletion: 3 weeks

CPT Codes and Prices:

Sequencing Index: 83912, 83894, 83891, 83898x27, 83904x54, 83909x54
Sequencing Known Familial Mutation: 83912, 83894, 83891, 83898, 83904x2, 83909x2
Targeted Deletion: 83891, 83894, 83900, 83912

Shipping Information

Forms:

 >> Gene Sequencing Requisition or DNA Requisition
 >> Prenatal Requisition

References:

1. Rinchik EM, Bultman SJ, Horsthemke B, Lee ST, Strunk KM, Spritz RA, Avidano KM, Jong MT, Nicholls RD. A gene for the mouse pink-eyed dilution locus and for human type II oculocutaneous albinism. Nature 1993; 361(6407): 72-76.

2. Durham-Pierre D, Gardner JM, Nakatsu Y, King RA, Francke U, Ching A, Aquaron R, del Marmol V, Brilliant MH. African origin of an intragenic deletion of the human P gene in tyrosinase positive oculocutaneous albinism. Nat. Genet. 1994; 7(2): 176-179.

Test Codes:

Sequencing Index: 6830
Sequencing Known Familial Mutation: 6831
Sequencing Prenatal (Known Familial Mutation Only): 6832
Targeted Deletion: 6833
Targeted Deletion Prenatal: 6834

Medical Genetics Laboratories
Baylor College of Medicine · Houston, TX 77030
Phone: 1-800-411-GENE · Fax: 713-798-2787
E-mail: