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Consent Form Recommended
Ordering Recommendation

Determine zygosity.

Mnemonic
TWIN ZYG
Methodology

Polymerase Chain Reaction/Fragment Analysis

Performed

Varies

Reported

5-10 days

New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
Collect

From each twin: Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B). Also acceptable: Buccal brushes.

Specimen Preparation

From each twin: Transport 3 mL whole blood (Min: 1 mL) Also acceptable: 2 buccal brushes.

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions
Remarks
Stability

Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable

Reference Interval

By report.

Interpretive Data

Background Information:
Characteristics:
Monozygotic twins originate from a single fertilized ovum dividing into two embryos, while dizygotic twins result from ovulation of two eggs during a single menstrual cycle.
Incidence:
Twins are delivered 1 in 77 Caucasian births; 70 percent are dizygotic and 30 percent are monozygotic.
Inheritance:
Multifactorial
Cause:
Dizygotic twinning is related to increased levels of maternal follicle stimulating hormone.
Clinical Sensitivity:
99 percent.
Methodology:
PCR followed by capillary electrophoresis; specimens are analyzed using 15 autosomal short tandem repeat markers (D8S11 79, D21S11, D7S820, CSF1PO, D3S1358, THO1, D13S317, D16S539, D2S1338, D19S433, vWa, TPOX, D18S51, D5S818 and FGA) and one gender marker (Amelogenin).
Analytic Sensitivity:
99 percent.
Limitations:
Diagnostic errors can occur due to rare sequence variations.

Compliance Category

Laboratory Developed Test (LDT)

Note

Results from both twins will be compared and reported; therefore a test must be ordered for and sample submitted from each individual.

Hotline History
N/A
CPT Codes

81265

Components
Component Test Code* Component Chart Name LOINC
0050547 Twin Zygosity Testing Interpretation
2001383 Twin Zygosity Testing Specimen
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • Fetal Zygosity
  • Mono/Dizygotic Differentiation
  • Newborn Zygosity
  • Zygosity, Twin Pre/Postnatal
Twin Zygosity Testing