[Use of microsatellites in zygosity diagnosis of twins]
1Ruijin Hospital, Shanghai Second Medical University, Shanghai Institute of Hypertension, Shanghai, 200025 P. R. China. f97075@guomai.sh.cn
Objective:
To diagnose zygosity of twins by microsatellite polymorphism.
Methods:
One hundred and eighty-four samples, including 69 pairs of twins with the same gender and 6 pairs of twins with different gender were recruited. Seventeen sib pairs were also collected for controls. Nine highly polymorphic microsatellite loci were amplified by polymerase chain reaction (PCR) using fluorescence-labeled primers and the products were sized by automated fragment analysis after electrophoresis and laser detection. Zygosity was diagnosed by comparing the concordance of the genotype of the 9 markers.
Results:
Sixty-three pairs of monozygotic (MZ) and 12 pairs of dizygotic (DZ) twins were assigned their zygosity by comparison of polymorphism of 9 microsatellite loci. Within each of the 63 monozygotic (MZ) pairs there was complete concordance. However, within each of the 12 dizygotic pairs and other 17 sib pairs, discordant loci were found. With five or six markers, the probability that any twin pair was MZ if all markers were concordant was 99% or 99.6%, respectively. With all the nine markers, the probability that any twin pair was MZ if all markers were concordant was 99.95%.
Conclusion:
The technology of gene scan and genotyping provides a rapid and reliable approach to zygosity detection.
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