Russell-Silver syndrome (11p15.5) Methylation/MLPA
|Disorders||Russell-Silver syndrome (RSS)|
|Clinical info||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||Methylation testing is useful to confirm a suspected diagnosis of RSS and to confirm the underlying etiology.|
|Associated Tests||Chromosome 7 Uniparental Disomy Studies (UPD)|
|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.
|Specimen Requirements||5 to 10 ml of peripheral blood collected in an EDTA (lavender top) Vacutainer tube is preferred. The minimal blood needed for reliable DNA isolation is 3 ml.|
|Transport||The specimen should be kept at room temperature and delivered via overnight shipping. FedEx is preferred. 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.|
|Turnaround time||3 weeks|
|Prenatal testing||Prenatal diagnosis for Russell-Silver syndrome via methylation analysis is not available.|
Molecular Diagnostic Lab
The Molecular Diagnostic Lab offers DNA analysis for many genetic disorders via gene sequencing, targeted mutation analysis, MLPA deletion/duplication testing, trinucleotide repeat analysis and next generation sequencing panels.