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Molecular Genetics Laboratory

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X-Linked Angelman-like Syndrome (SLC9A6 Sequence Analysis)

  • Synonyms: X-Linked Syndromic Mental Retardation; Christianson Type
  • LIS Mnemonic: MBSLC9A6SEQ

    Collect

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

    Volume Required

    5 ml whole blood or 5 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

81406

Disease Information

Clinical Features:

X-linked Angelman-like syndrome is a mental retardation syndrome associated with microcephaly, seizures, ataxia, and absent speech. Many identified patients also display a happy demeanor with frequent smiling and spontaneous laughter reminiscent of Angelman syndrome. Affected individuals appear normal at birth, then display deceleration of head growth in the first year of life and a thin body habitus. The clinical spectrum of features seems to resemble Angelman syndrome in younger patients and Christianson syndrome in older patients. There appears to be range of phenotypes in carrier females, from mental retardation to absence of symptoms.

Molecular Genetics:

Mutations in the gene SLC9A6 (Xq26.3) lead to X-linked Angelman-like syndrome. Truncating, splice site and nonsense mutations in the SLC9A6 gene have been identified in 6% of patients with an Angelman-like phenotype that were negative for mutations in the MECP2 gene and the 15q region.

Test Methods:

We offer DNA sequence analysis of the entire coding region of the SLC9A6 gene. PCR amplification and sequence analysis 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. Mutations in promoters, deep intronic regions and other regulatory regions will not be identified with this assay.

Detection Rate:

Mutations in the SLC9A6 gene are identified in ~6% of patients with an Angelman-like phenotype that were negative for mutations in the MECP2 gene and the 15q region.

Related Tests:

Known mutation analysis of the SLC9A6 gene is available to family members for mutations previously identified by sequence analysis. Prenatal Testing is available to individuals who are confirmed carriers of mutations in the SLC9A6 gene. Please contact the laboratory director to discuss appropriate testing prior to collecting a prenatal specimen. Angelman Studies by Methylation Specific PCR Rett Syndrome: MECP2 Sequence and Deletion/Duplication Analysis

Results:

Test results with interpretation will be mailed and/or faxed to the referring physician 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, assess the risk to other first degree relatives and to facilitate testing of at - risk family members.

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215-590-5221