ABCA4-RELATED DISORDERS

Includes: Stargardt Disease, Cone-Rod Dystrophy, and Retinitis Pigmentosa

ABCA4 Sequencing

DNA ANALYSIS

Stargardt disease 1 (STGD1) is an autosomal recessive retinal disorder characterized by juvenile-onset macular dystrophy, alterations of the peripheral retina, and subretinal deposition of lipofuscin-like material. It is one of the most frequent causes of macular degeneration in childhood. The ABCA4 gene (ATP-binding cassette, sub-family A, member 4) encodes a photoreceptor-specific ATP-binding cassette transporter of retinaldehyde or a related derivative essential to the visual cycle. Mutations in the ABCA4 gene are found in patients diagnosed with Stargardt disease as well as in patients diagnosed with retinitis pigmentosa and cone-rod dystrophy. Sequence analysis of the entire ABCA4 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 50 exons contained in the ABCA4 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. Prior to any genetic testing, we recommend genetic counseling and we request that the subject sign our consent statement and submit it with the sample. To receive forms, additional information or specimen collection kits, please contact the laboratory. Please call laboratory for specific requirements for prenatal testing.

Turnaround Time:

Index: 4 weeks

CPT Codes and Prices:

Index: 83912, 83894, 83891, 83898x50, 83904x100, 83909x100
Known Familial Mutation: 83912, 83894, 83891, 83898, 83904x2, 83909x2

Shipping Information

Forms:

>> Gene Sequencing Requisition
>> Prenatal Requisition

References:

Allikmets R, Singh N, Sun H, Shroyer NF, Hutchinson A, Chidambaram A, Gerrard B, Baird L, Stauffer D, Peiffer A, Rattner A, Smallwood P, Li Y, Anderson KL, Lewis RA, Nathans J, Leppert M, Dean M, Lupski JR. A photoreceptor cell-specific ATP-binding transporter gene (ABCR) is mutated in recessive Stargardt macular dystrophy. Nat. Genet. 1997; 15: 236-246.
Allikmets R, Shroyer NF, Singh N, Seddon JM, Lewis RA, Bernstein PS, Peiffer A, Zabriskie NA, Li Y, Hutchinson A, Dean M, Lupski JR, Leppert M. Mutation of the Stargardt disease gene (ABCR) in age-related macular degeneration. Science. 1997; 277: 1805-1807.

Test Codes:

Index: 6600
Known Familial Mutation: 6601
Prenatal (Known Familial Mutation Only): 6602