Twin Zygosity Testing
Twin zygosity testing is performed to determine if two children born of the same pregnancy are identical or fraternal twins.
Fraternal Twins are conceived from two different eggs and sperm. When twins are conceived with different eggs, they will share some of their DNA (just like any sibling), but there will be differences.
Identical Twins are conceived from one fertilized egg which splits into two embryos early in development. When twins are conceived from one egg and one sperm, they will have exactly the same DNA.
Through DNA twin testing, PTC Laboratories is able to determine positively if twins are fraternal. If twins match at all tested DNA loci, then PTC Laboratories will provide a statistic greater than 99.99% in favor of the tested individuals being identical