Background:
Zygosity testing is the process through which DNA sequences are compared to assess whether individuals born from a multiple gestation (twins, triplets, etc.) are monozygotic (identical) or dizygotic (fraternal).
Methodology:
PCR: analysis for short tandem repeats for nine polymorphic loci. Monozygosity can be excluded if both twins have inherited different polymorphic markers from their parents. Monozygosity can be included at > 99% if all markers tested are identical.
Specimen Requirements:
Blood: EDTA or ACD (Solution Aor B):
- Adult: 5mL
- Child: 5mL
- Infant: 2-3mL
Saliva: 2 ORAgene Saliva Kit(s) (OGR-500)
Skin Fibroblast: Punch Biopsy, or 2 T-25 confluent flasks
Prenatal:
- Direct Amniotic Fluid (10-20mL)
- Direct CVS
- Cultured Amnio or CVS (2-T25 flasks)
DNA: 100ng at a minimum of 50-100ng/µL (DNA must be extracted in a CLIA-certified laboratory or a laboratory meeting equivalent requirements as determined by the CAP and/or CMS)
Notice Regarding Molecular Genetic Testing on CVS or Amniotic Fluid Specimens:
- Maternal cell rule-out testing will be performed on all prenatal specimens received.Please provide maternal blood in addition to the fetal specimen.Additional charges apply for the maternal cell rule-out test.
- All genetic testing performed on Direct CVS or Direct Amniotic Fluid specimens will be confirmed on cell cultures prepared by Knight Diagnostic Laboratories.Cell cultures will be prepared from the specimen received.Additional charges apply for confirmatory testing.
For routine testing of blood and saliva (or DNA extracted from them), KDL does NOT accept samples from patients within two (2) weeks of a packed cell/platelet transfusion or within four (4) weeks of a whole blood transfusion. For extraordinary circumstances, where testing must be performed outside of the above windows, please contact our lab.
A REQUISITION FORM MUST ACCOMPANY ALL SAMPLES. Please include detailed clinical information.
Test Performed (Days):
Weekly
Turn Around Time:
7 – 10 Days
Shipment Sensitivity Requirements:
- Package and ship specimen to remain cold, but not frozen.
- Ship via overnight express, using the FedEx priority overnight label provided.
- Contact Client Services for shipping kits and instructions at (855) 535-1522.
References:
Additional Info:
This testing can also be medically important in the case of bone marrow and organ transplantation. Please call Client Services at (855) 535-1522 for more information.