NGS Non-immune Hydrops Panel
|Disorder||Non-immune Hydrops Fetalis|
Non-immune hydrops fetalis can result from numerous etiologies. Inborn errors of metabolism, specifically some lysosomal storage disorders, have been shown to be a cause of some cases of non-immune hydrops. Genes asscoaited with RASopathies, certain skeletal dysplasias, and lymphedema disorders are included on this expanded 87-gene sequencing panel.
|Indications||This panel may be particularly useful for prenatal cases when enzyme testing is not available and the single gene approach is not cost efficient.
For patients with a specific suspected storage disease, enzyme analysis or individual gene sequencing should be considered first.
|Detection||The current design of the NGS Non-immune hydrops panel covers the coding region for all 87 genes and the flanking intronic sequences. This method allows for analysis of greater than 98% of the targeted sequence for the detection of nucleotide substitutions and small deletions and duplications. Large deletions and duplications will not be detected by this panel. Mutations and variants identified on the panel are confirmed with Sanger sequencing. All novel and apparently pathogenic changes are reported when found within the coding region as well as within 10 basepairs of each intron/exon boundary for each gene. Promoter and 3' untranslated sequences are not included in the current analysis. It should be noted that the current protocol is not specifically designed to detect copy number alterations.
We recommend further array-based testing to more accurately address the concerns of dosage alterations. The Cytogenetic Laboratory at GGC offers a high resolution testing whole genome SNP microarray. The GGC Diagnostic Laboratory Directors are available for further consultation regarding the limitations of the NGS and array testing procedures.
Effective January 1, 2017, all NGS panels are performed on an exome backbone with the potential for reflex to whole exome sequencing at a reduced cost. Please contact the laboratory to discuss the requirements for exome sequencing.
|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.
For prenatal specimens, 2x T25 flasks of cultured amniocytes are requested. Maternal cell contamination studies are required for all prenatal molecular tests. Additional fees for cell culture and maternal cell contamination may apply. Contact the laboratory prior to sending a prenatal specimen.
|Transport||Blood: 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.
Prenatal Specimen: The specimen should be kept at room temperature and delivered via overnight shipping. FedEx is preferred. It should shipped at room temperature. Do not freeze the specimen.
|Turnaround time||8-10 weeks|
|Prenatal testing||The panel can be performed on prenatal specimens when ultrasound findings are suggestive of hydrops fetalis. Please be aware that due to the current turnaround time for this test, it is unlikely results will be available in time for families to use this information for pregnancy management. These results will be most helpful for families interested in recurrence risk information.
If the pathogenic mutation(s) are identified in an affected individual using this panel, prenatal diagnosis is available for future pregnancies. Sanger sequencing will be used for prenatal diagnosis when there is a known familial mutation. 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.
Insurance billing is available for this test. The Insurance Billing Form is required along with copies of the authorization or letter of agreement from the insurance company.
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.