OCULOCUTANEOUS ALBINISM TYPE 3 (OCA3)

TYRP1 Sequencing

DNA ANALYSIS

Also see: 6825 - Oculocutaneous Albinism Type 1 - TYR Sequencing; Oculocutaneous Albinism Type 2 - OCA2 Sequencing and Targeted Deletion Analysis; 6840 - Oculocutaneous Albinism Type 4 - SLC45A2 Sequencing

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. OCA3 is rare compared to OCA1 and OCA2. It is caused by mutations in the Tyrosinase-related protein 1 (TYRP1) gene. Sequence analysis of the entire TYRP1 gene is 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 all the seven coding exons contained in the TYRP1 gene coding region 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.

Specimen Requirements:

Blood: EDTA (purple-top) tubes: Adults: 14 cc; Child: 6 cc; Infant: 2-3 cc
Requisition form must accompany the specimen. To receive forms, additional information or specimen collection kits, please contact the laboratory. Please call our laboratory for specific requirements for prenatal testing.

Turnaround Time:

Index: 4 weeks
Known Familial Mutation: 3 weeks

CPT Codes and Prices:

Index: 83912, 83894, 83891, 83898x7, 83904x14, 83909x14
Known Familial Mutation: 83912, 83894, 83891, 83898, 83904x2, 83909x2

Shipping Information

Forms:

>> Gene Sequencing Requisition
>> Prenatal Requisition

References:

Boissy, R.E. et al (1996). Mutation in and lack of expression of tyrosinase-related protein-1 (TRP-1) in melanocytes from an individual with brown oculocutaneous albinism: a new subtype of albinism classified as "OCA3". Am. J. Hum. Genet. 58: 1145-1156.

Test Codes:

Index: 6835
Known Familial Mutation: 6836
Prenatal (Known Familial Mutation Only): 6837