Zygosity Testing (Multiple Births)

Casandra

Casandra Test Code MC26711Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID MULTCPT Codes 81265, 81266, 88233, 88235, 88240

Zygosity Testing (Multiple Births)

Clinical Use

Use

This test is crucial for determining genetic risk in cases where one twin or triplet is affected with a genetic disorder for which specific genetic testing is unavailable or the available testing is uninformative. It is also useful for assessing prenatal risks when one fetus of multiples is known to be affected. Moreover, it aids in organ or bone marrow transplantation compatibility testing and serves familial or parental interest, providing pivotal genetic insights for multiples and their family planning.

Special Instructions

The test requires a specimen from each multiple and specimens from both parents are recommended for more accurate results. Informed consent is required for New York clients. DNA from twins and their parents is used to determine if the twins are identical or fraternal, using Polymerase Chain Reaction (PCR) and microsatellite markers. The availability of a specimen from all family members provides the most accurate results, and any absence may render markers less informative.

Limitations

This test is not designed for medico-legal or forensic purposes, as chain of custody documentation is unavailable. The results are suggestive and should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in interpretation may occur if information is incomplete or inaccurate. Nonpaternity can be detected but is not the primary focus of this test. Specimen availability from all family members enhances accuracy, but if parental blood is not available, the results may be less informative.

Test Details

New York Approved