Pendred Syndrome

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PENDRED SYNDROME

Gene Symbol: SLC26A4

Chromosomal Locus: 7q31
 
Protein: Solute Carrier Family 26, member 4
 
Pseudonyms: DFNB4, NS-EVA, PDS, Pendrin
 
TURNAROUND TIME: 4 weeks
  
TESTING METHODOLOGY: Polymerase chain reaction (PCR) and DNA Sequencing of all 21 exons, and their intron-exon borders.
 
SPECIMEN REQUIREMENTS:
  • Collect: Prefer two 5ml whole blood EDTA (lavender top) tube.
  • Min. Collection: 0.7 ml whole blood EDTA.
  • Transport: blood EDTA at Room Temp shipped regular next day air (No Saturday delivery; store specimen at 4°C and ship Monday).
  • Stability: Ambient: up to 7 days; Refrigerated: 2 weeks. Frozen: unacceptable
  • Unacceptable Conditions: Serum. Frozen or severely hemolyzed blood. Clotted blood.
  • Prenatal testing: Direct: 5ml direct unspun amniotic fluid or 15mg CVS tissue with a backup flask growing. Culture: confluent T25 flask. Maternal blood sample is required for maternal cell contamination studies.
A Molecular Genetics Laboratory Test Requisition must accompany the specimen. Contact the Molecular Laboratory at 918-502-1721 to obtain further information.
Note: Counseling and informed consent are recommended for genetic testing. A consent form is available as a resource but not required.
 
INTERPRETATIVE DATA:
 
Incidence: Unknown, however estimated to account for 7.5% of all congenital deafness.
 
Inheritance: Autosomal recessive.
 
Disease Characteristics: Sensorineural hearing impairment that is usually congenital, non-progressive, and severe to profound; enlarged vestibular aqueduct [EVA]); abnormal perchlorate discharge test or goiter, generally occurring in late childhood or adolescence. Mondini malformation may also be present. Isolated enlarged vestibular aqueduct [EVA]-related hearing loss may occur with a single mutation.
 
Molecular Genetic Mechanism: A variety of missense, nonsense and insertion/deletion mutations have been described in the gene.
 
Clinical Sensitivity: 50%- 90%
 
Analytic Sensitivity: >99%
 
Test Limitations: Mutations located outside the tested region will not be detected. Rare diagnostic errors can occur due to primer or probe site mutations or rare polymorphisms.
 
INDICATIONS FOR USE:
  • To determine whether a hearing defect in a child is hereditary.
  • To identify the potential for abnormal thyroid function and risk of goiter.
  • To assess the risk of having a child with hearing loss.
ADDITIONAL REFERENCES:
OMIM - SLC26A4: www.omim.org/entry/605646
Gene Reviews - Pendred : www.ncbi.nlm.nih.gov/pubmed/20301640
Gene Reviews - hereditary hearing loss overview: www.ncbi.nlm.nih.gov/pubmed/20301607