Russell-Silver Syndrome Methylation-Specific MLPA

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

• Russell-Silver syndrome (RSS)

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.

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.

multiplex ligation-dependent probe amplification (MLPA)

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.

The preferred sample type is 3-5 ml of peripheral blood collected in an EDTA (purple top) tube. Extracted DNA and saliva are also accepted for this test. Saliva samples must be submitted in an approved saliva kit. Contact the lab to receive a saliva kit or to have one sent to your patient.

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 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.