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Lab Dept:
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Anatomic Pathology
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Test Name:
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ANOPHTHALMIA, MICROPHTHALMIA (SOX2) SEQUENCING
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General Information
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Lab Order Codes:
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SOX (Blood or Buccal Swab)
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Synonyms:
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Developmental Eye Disorders
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CPT Codes:
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81479 – Unlisted Molecular Pathology procedure (SOX2 Sequencing)
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Test Includes:
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Using genomic DNA, bi-directional sequence of the coding portion of the SOX2 gene (single large exon) is obtained and analyzed. Mutation found in the first of a family to be tested and is confirmed by repeat analysis using sequencing, restriction fragment analysis, or another appropriate method.
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Logistics
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Test Indications:
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Several developmental eye disorders have a known genetic basis including microphthalmia and anophthalmia. Anophthalmia is the complete absence of the globe, or bulb, of the eye and hence the most structural eye malformation. A milder form is microphthalmia, where total axial length of the eye globe is the least two standard deviations below the mean for age. Simple microphthalmia refers to a structurally normal eye with short total axial length. In each of these conditions, the eyelids, conjunctiva and lacrimal apparatus are normal. In complex microphthalmia, additional abnormalities are present and may include anterior segment dysgenesis, cataract, persistent hyperplastic primary vitreous, chorioretinal coloboma and/or retinal dysplasia. In addition, anophthalmia and microphthalmia may be seen in association with various genetic syndromes or chromosome abnormalities. Mutations in the SOX2 and SIX6 genes leading to haploinsufficiency may be associated with hearing loss, developmental delay, esophageal atresia, genitourinary abnormalities, myopathy, and spastic diplegia. Hemizygosity for SIX6 has been seen in some cases of bilateral anophthalmia due to interstitial chromosome deletions. Homozygosity for PAX6 mutation has also been associated with anophthalmia.
Reasons for referral:
1. Confirmation of a clinical diagnosis
2. Genetic counseling
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Lab Testing Sections:
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Anatomic Pathology - Sendouts
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Referred to:
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GeneDx, Inc. (GDX#: 132)
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Phone Numbers:
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MIN Lab: 612-813-6280
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STP Lab: 651-220-6550
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Test Availability:
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Daily, 24 hours (Preferred draws are Sunday - Thursday as specimens can only be received at the reference lab Monday - Friday. Specimens collected Friday or Saturday will be held for shipment on Monday.)
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Turnaround Time:
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8 - 10 weeks for new patients
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Special Instructions:
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A GeneDx signed request form must be sent with any patient or specimen to the laboratory.
SOX2 can be tested using cells obtained by swabbing the buccal mucosa (inside of cheek). Buccal specimens are not accepted on children under 6 months of age. Buccal swab collection kits are available from GeneDx (ph. 301-519-2100). Buccal Kit info link: http://www.genedx.com/buccal_swab_kits.php
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Specimen
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Specimen Type:
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Whole blood
Buccal cell swab (preferred specimen)
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Container:
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Blood: Lavender top (EDTA) tube
Buccal Smear: Cytobrush Plus Cell CollectorŽ kit
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Draw Volume:
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1 - 5 mL blood
2 swabs from the Cytobrush Plus Cell CollectorŽ kit
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Processed Volume:
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Same as Draw Volume
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Collection:
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Routine venipuncture for blood specimens, invert gently to mix
Buccal swab kit for buccal swabs:
Buccal Cell Collection procedure:
1. Remove a swab from the Buccal swab kit touching only the “stick” end.
2. Do Not rinse mouth before starting. Have the individual open his/her mouth. Twirl the swab on the inner cheek for 30 seconds. Do Not scrape so hard that the cheek bleeds.
3. Place the swab end in the labeled tube. Cut the “stick” with scissors at the level of the top of the tube. Replace cap and close completely.
4. Repeat the process with another swab on the opposite cheek.
5. Send the kit to the lab for processing and mailing.
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Special Processing:
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Lab Staff: Send whole blood in original collection container labeled with patient name, date of birth and medical record number, including signed consent form and requisition, with a cool pack in warm weather, via overnight or second-day courier so that the sample will arrive at GeneDx, Inc. on a weekday (Monday through Friday). Samples drawn on Friday or Saturday should be held at refrigerated temperatures for shipment on Sunday. Do not freeze.
Note: Specimens may be stored at refrigerated temperatures for up to 7 days prior to shipping.
Mail the Cytobrush Plus Cell CollectorŽ kit, including signed consent form and requisition, by regular mail to GeneDx in the included envelope.
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Patient Preparation:
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For buccal cell collection, Do Not have the patient rinse his/her mouth.
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Sample Rejection:
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Unrefrigerated specimens older than 48 hours’ clotted or hemolyzed for blood; frozen specimens; mislabeled or unlabeled specimens
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Interpretive
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Reference Range:
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No mutations detected
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Critical Values:
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N/A
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Limitations:
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Buccal specimens are not acceptable on children under 6 months of age.
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Methodology:
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Bi-directional sequence analysis
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References:
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Gene Dx, Inc March 2012
(301) 519-2100 Fax (301) 519-2892
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Updates:
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1/29/2013: CPT 2013 update
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