Beckwith-Wiedemann Syndrome Methylation/MLPA
|Disorders||Beckwith-Wiedemann syndrome (BWS)|
|Clinical info||BWS is the most common overgrowth syndrome characterized by large organs and body size. Macroglossia, ear lobe creases, helical creases, and omphalocele are common features as well. Patients with BWS are at an increased risk for embryonal tumors in childhood. These individuals typically have normal intelligence and attain a normal height and weight in adulthood. BWS is casued by alterations in methylation at two imprinting centers at 11p15.5.|
|Indications||Methylation testing is useful to confirm a suspected diagnosis of BWS and to confirm the underlying etiology.|
|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 75% of cases of BWS. This includes about 55% of cases with an isolated imprinting defect, 20% of cases with paternal UPD, and less than 1% of cases with a deletion or duplication.
|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 Beckwith-Wiedemann 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.