Walker-Warburg Syndrome

CPT: 81479
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Test Details

Synonyms

  • FUKUTIN
  • Jewish Heritage Test

Use

Detection of the c.1167insA mutation on the FKTN gene, which accounts for approximately 99% of Walker-Warburg carriers in the Ashkenazi Jewish population.

Limitations

This test detects only the c.1167insA mutation

Methodology

Polymerase chain reaction (PCR) and primer extension

Additional Information

Walker-Warburg syndrome (WWS, OMIM 236070) is an inherited, autosomal recessive disorder characterized by a triad of brain malformations, eye abnormalities, and congenital muscular dystrophy. The clinical findings include muscle weakness, hypotonia, feeding difficulties, blindness, seizures, and mal genital anomalies. Characteristic brain malformations include cobblestone lissencephaly, among other findings. Life expectancy is less than three years. The disease has an elevated prevalence in the Ashkenazi Jewish population, with a carrier rate of 1 in 150. When both parents are carriers of WWS, there is a 25% chance with each pregnancy of having a child with the disease. Prenatal diagnosis is available.

Molecular genetic testing for WWS encompasses one founder mutation in the gene encoding fukutin (FKTN gene, 9q31). Testing for the c.1167insA mutation identifies approximately 99% of WWS carriers in the Ashkenazi Jewish population. The carrier frequency in the non-Ashkenazi Jewish population has not been determined. A negative result decreases the likelihood that the individual is a carrier but cannot completely eliminate the possibility. The presence of a rare mutation cannot be ruled out. DNA test results must be combined with clinical information for the most accurate interpretation.

Specimen Requirements

Specimen

Whole blood, amniotic fluid, chorionic villus sample (CVS) (Submission of maternal blood is required for fetal testing.), or LabCorp buccal swab kit (Buccal swab collection kit contains instructions for use of a buccal swab.)

Volume

7 mL whole blood, 10 mL amniotic fluid, 20 mg CVS, or LabCorp buccal swab kit

Minimum Volume

3 mL whole blood, 5 mL amniotic fluid, 10 mg CVS, or two buccal swabs

Container

Lavender-top (EDTA) tube, yellow-top (ACD) tube, sterile plastic conical tube or two confluent T-25 flasks for fetal testing, or LabCorp buccal swab kit

Storage Instructions

Maintain specimen at room temperature or refrigerate at 4°C

Causes for Rejection

Frozen specimen; hemolysis; quantity not sufficient for analysis; improper container; one buccal swab; wet buccal swab

Clinical Information

References

Chang W, Winder TL, LeDuc CA, et al. Founder Fukutin mutation causes Walker-Warburg syndrome in four Ashkenazi Jewish Families. Prenat Diagn. 2009 Jun; 29(6):560-569.
Manzini MC, Gleason D, Chang BS, et al. Ethnically diverse causes of Walker-Warburg syndrome (WWS): FCMD mutations are a more common cause of WWS outside of the Middle East. Hum Mutat. 2008 Nov; 29(11):E231-E241.

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
511480 Walker-Warburg Syndrome 511481 Walker-Warburg Syndrome 53861-1
511480 Walker-Warburg Syndrome 511964 PDF 51969-4
511480 Walker-Warburg Syndrome 511005 Jewish Heritage Putaway N/A

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