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Molecular Genetics Laboratory

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Mowat-Wilson Syndrome (ZEB2 Sequence and Deletion/Duplication Analysis)

  • LIS Mnemonic: MBZEB2FS

    Collect

    Collect whole blood in a purple top (EDTA) tube (preferred). Extracted DNA is also acceptable.

    Volume Required

    5 ml whole blood or 4 ug extracted DNA

    Minimum Required

    3 ml whole blood

    Transport

    Refrigerate sample until shipment. Send the sample at room temperature with overnight delivery for receipt Monday through Friday within 24 hours of collection.

    Stability

    Whole blood can be refrigerated until shipment.

    Unacceptable conditions

    Heparinized specimens, severely hemolyzed specimens, frozen, clotted or possibly commingled specimens, blood in non-sterile or leaky containers, mislabeled or inappropriately labeled specimens.

    Specimen Handling

    Do not heat, freeze or centrifuge blood before shipment. Refrigerate sample until shipment.

Days Performed

Mon - Fri 9:00am to 4:00pm

Reported

4-6 weeks

CPT

81405, 81404

Disease Information

Clinical Features:

Mowat-Wilson syndrome (MWS) is characterized by intellectual disability, severe speech impairment, Hirschsprung disease or severe constipation, genitourinary anomalies, congenital heart defects, agenesis or hypogenesis of the corpus callosum, eye defects (microphthalmia and Axenfeld anomaly), growth retardation, epilepsy, and microcephaly. Typical facial features include medially flared broad eyebrows, pointed chin, hypertelorism, uplifted ear lobes with a central depression and prominent columella.

Molecular Genetics:

All patients with a confirmed clinical diagnosis of MWS have mutations in the ZEB2 gene. ZEB2 is located on chromosome 2p22 and it encodes Smad-interacting protein-1 (SMADIP1). Missense, splice site, nonsense, and large deletions have been identified in the ZEB2 gene.

Test Methods:

We offer DNA sequence analysis and deletion/duplication testing of the entire coding region of the ZEB2 gene. These tests can be ordered as a panel or individually. PCR amplification and sequence analysis is performed on the coding exon including splice junctions. The patient’s gene sequence is compared to a reference sequence. Sequence variants are classified as mutations, variants of unknown significance or benign variants unrelated to disease. Variants of unknown significance may warrant further studies in the patient and other family members. Mutations in promoters, deep intronic regions and other regulatory regions will not be identified with this assay. Large deletions and duplications will be detected using multiplex ligation-dependent probe amplification assay (MLPA).

Detection Rate:

Sequence analysis of the ZEB2 gene detects point mutations in roughly 80% of patients with MWS. More than 50% of these mutations are present in exon 8 of the ZEB2 gene. Large deletions within the ZEB2 gene are detected in roughly 17% of patients with MWS. An additional 2-3% of patients have chromosomal rearrangements that disrupt the ZEB2 gene. The majority of cases are de novo.

Related Tests:

Known mutation analysis is available to family members for mutations previously identified by sequence analysis.

Results:

Test results with interpretation will be mailed and/or faxed to the referring physician or send out lab following completion of the test. Additional reports will be provided as requested.

Utility:

The clinical utility of the assay is to support a clinical diagnosis of the disease, facilitate genetic counseling, and assess the risk to other first degree relatives and to facilitate testing of at - risk family members.

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215-590-5221