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Twin Zygosity Testing
0050547
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.
Submit With Order
Consent Form RecommendedConsent Form Recommended
ARUP Consult®
Disease Topics
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 Statement B: This test was developed and its performance characteristics determined by ARUP Laboratories. The U.S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

Note
Results from both twins will be compared and reported; therefore a test must be ordered for and sample submitted from each individual.
CPT Code(s)
81265
Components
Component Test Code*Component Chart NameLOINC
0050547Twin Zygosity Testing Interpretation
2001383Twin 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