Russell-Silver syndrome (RSS) : RSS Methylation-Specific (MLPA)

Test Information

RSS Methylation-Specific (MLPA) is a molecular test used to detect copy number variants or methylation abnormalities associated with Russell-Silver syndrome (RSS).

Turnaround Time

3 weeks

CPT Code(s)

81401

Cost

$600

Clinical Information

Intrauterine growth restriction (IUGR) and postnatal growth deficiency are primary features of Russell-Silver syndrome. Individuals with RSS also commonly have developmental delay and characteristic triangular facies. These patients will not usually attain normal height or weight as adults. RSS is casued by alterations in methylation at 11p15.5 as well as by uniparental disomy of chromosome 7.

Indications

Molecular testing is useful to confirm the diagnosis and to identify the disease causing mutations within a family to allow for carrier testing and prenatal diagnosis.

Methodology

multiplex ligation-dependent probe amplification (MLPA)

Detection

A methylation sensitive MLPA assay is used to determine methylation status at the two imprinting centers and to identify microdeletions or duplications. If an abnormal methylation pattern is identified, then pyrosequencing is performed to quantify the methylation at these sites.

This testing will detect approximately 50% of cases of Russell-Silver syndrome. The majority of these cases have isolated imprinting defects while less than 1% have microdeletions or duplications.

Associated Tests

Specimen Requirements

5 to 7 ml of peripheral blood collected in an EDTA (lavender top) tube is the preferred specimen type. The minimal blood needed for reliable DNA isolation is 3 ml. Extracted DNA, dried blood spots, and saliva are also accepted for this test.

Transport Instructions

The specimen should be kept at room temperature and delivered via overnight shipping. If shipment is delayed by one or two days, the specimen should be refrigerated and shipped at room temperature. Do not freeze the specimen. Samples collected on Friday can be safely designated for Monday delivery.

Prenatal Testing Information

Prenatal diagnosis is available if the familial mutations are known. Additional fees for cell culture and maternal cell contamination may apply. Maternal cell contamination studies are required for all prenatal molecular tests. Contact the laboratory prior to sending a prenatal specimen.

Have Questions Need Support?

Call our laboratory at 1-800-473-9411 or contact one of our Laboratory Genetic Counselors for assistance.
Robin Fletcher, MS, CGC
Kellie Walden, MS, CGC

Methylation Analysis, Methylation-Specific MLPA, MLPA, Molecular Testing, Other Molecular Testing
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