Condition Description

Genes (0)


Twins can be either monozygotic (identical) or dizygotic (non-identical). Identifying zygosity of twins is essential in diagnosing and treatment of certain genetic conditions. Testing may be performed on prenatal and postnatal samples.Samples from the twins, as well as both maternal and paternal blood, must be submitted. Amniocytes, chorionic villus, or blood samples from the twins can be used for analysis.


Comparative analysis of DNA samples has been conducted using PCR of polymorphic sites at the following fifteen markers: D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818, FGA. Fragment analysis was performed using capillary electrophoresis.

Parental samples are used to determine likelihood of dizygotic twins having the same allelic pattern as monozygotic twins.

Detection and Reference Range

Over 99% of twin pairs tested will be determined to be monozygotic or dizygotic.
Reference Range
Qualitative assay.

Specimen Requirements

Listed below are EGL's preferred sample criteria. For any questions, please call 470.378.2200 and ask to speak with a laboratory genetic counselor (
Submit only 1 of the following specimen types
DNA, Isolated

Isolation using the Perkin Elmer™Chemagen™ Chemagen™ Automated Extraction method or Qiagen™ Puregene kit for DNA extraction is recommended.
Collection and Shipping
Refrigerate until time of shipment in 100 ng/µL in TE buffer. Ship sample at room temperature with overnight delivery.
Whole Blood (EDTA)

EDTA (Purple Top)
Infants and Young Children (<2 years of age): 2-3 ml
Children > 2 years of age to 10 years old: 3-5 ml
Older Children & Adults: 5-10 ml
Autopsy: 2-3 ml unclotted cord or cardiac blood
Collection and Shipping
Ship sample at room temperature for receipt at EGL within 72 hours of collection. Do not freeze.

How to Order

Requisition Forms