Objective: Twin zygosity determinations can be performed with anthropologic, serologic and genetic markers; however, these methods are more than occasionally inefficient, often expensive and sometimes inaccurate. We used microsatellites as DNA markers and developed a largely automated, rapid and efficient method of determining zygosity.
Study design: We used five highly polymorphic short tandem repeat loci, coamplified by polymerase chain reaction (PCR) using fluorescence-labeled primers. Thirty-six samples were simultaneously analyzed by electrophoresis and laser detection. The PCR products were sized by automated fragment analysis.
Results: We typed 132 pairs of monozygotic (MZ) and dizygotic (DZ) twins. With five markers, the probability that any twin pair was MZ if all markers were concordant was 99%.
Conclusion: This method is a rapid and reliable approach to zygosity detection.