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 A or B):
- Adult: 5mL
- Child: 5mL
- Infant: 2-3mL
Saliva: 2 ORAgene Saliva Kit(s) (OGR-500) used according to manufacturer instructions. Please contact KDL Client Services for a Saliva Collection Kit for patients that cannot provide a blood sample.
Assisted Saliva: 4 ORAgene™ Assisted Saliva Collection Kits (OGR-575) used according to manufacturer instructions. Please contact KDL Client Services for a Saliva Collection Kit for patients that cannot provide a blood sample.
Skin Fibroblast: Punch Biopsy, or 2 T-25 confluent flasks
Prenatal:
- Direct Amniotic Fluid (10-20mL)
- Direct CVS
- Direct POC
- Cultured Amnio
- Cultured CVS (2 T-25 flasks)
- Cultured Fetal Tissue: Product of Conception (2 T-25 flasks)
- Cord Blood (1-2mL)
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 Prenatal Specimens:
Maternal cell rule-out testing will be performed on all prenatal specimens received. Please provide maternal blood (or saliva) in addition to the fetal specimen. Additional charges apply for the maternal cell rule-out test.
For routine testing of blood and saliva (or DNA extracted from these specimens), 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 within of the above windows, please contact the laboratory.
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.