Molecular Genetics Laboratory

Laboratory Update

Testing for the Noonan spectrum of disorders is now available at The Children’s Hospital of Philadelphia Molecular Genetics Laboratory.

Mental Retardation, Stereotypic Movements, Epilepsy, and/or Cerebral Malformations (MEF2C)

  • LIS Mnemonic: MBMEF2CSEQ

    Collect

    Collect whole blood in a purple top (EDTA) tube.

    Volume Required

    5ml

    Minimum Required

    3ml

    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

Seq & Del/dup- 81479 x 2; Sequence Only- 81479; Del/dup Only- 81479; Known Point Mutation- 81479

Disease Information

Clinical Features:

Mutations in the MEF2C gene result in an a distinct phenotype that is characterized by severe intellectual disability, hypotonia, epilepsy, stereotypic movements, lack of speech development and cerebral malformations. Patients can also present with mild dysmorphic features. There is phenotypic overlap between patients with MEF2C mutations and atypical Rett syndrome patients.

Molecular Genetics:

MEF2C is located on chromosome 5q14 and it encodes a transcription factor called myocyte enhancer factor 2C, which plays an important role in multiple embryological processes including cardiogenesis and neurogenesis.

Missense, splice site, nonsense, and large deletions have been identified in this gene. Mutations are inherited in an autosomal dominant pattern and are typically de novo. Germline mosaicism has not been reported previously.

Test Methods:

We offer DNA sequence analysis of the entire coding region. PCR amplification and sequencing is performed on all coding exons including splice junctions. The patient’s gene sequence is then 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.

Detection Rate:

In a large study of 362 patients with mental retardation, mutations in the MEF2C gene were identified in 1.1% of patients (Zweier et al. 2010., Human Mutation; 31: 722-723).

Related Tests:

Atypical Rett syndrome (CDKL5 and FOXG1 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.

Remarks

Whole blood in EDTA purple top tubes is the preferred sample. High molecular weight genomic DNA, cheek epithelial cells, or other samples containing DNA may be acceptable. Contact the laboratory for specific instructions regarding such samples before sending the sample.

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