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Updated: Aug 19, 2026

FISH for Pre-implantation Genetic Diagnosis
Published on: February 23, 2011
How many markers or how many alleles per system are appropriate in zygosity testing?
1Institute of Human Genetics and Anthropology, Heinrich-Heine-University, Düsseldorf, Germany.
Abstract:
Due to the development in DNA-PCR-technique more and more systems with a high number of alleles have been established in twin diagnosis. Because of their high effectiveness in resolving of genetic questions it is not amazing that some authors have postulated the thesis that typing of 5 to 10 DNA-PCR systems can prove monozygosity. For this paper the use of different systems (conventional and PCR systems) has been tested for twin diagnosis and the observed effects are discussed.
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Some of Mendel’s crosses examined three pairs of contrasting characteristics. Such a cross is called a trihybrid cross. A trihybrid cross is a combination of three individual monohybrid crosses. For example, plant height (tall vs. short), seed shape (round vs. wrinkled), and seed color (yellow vs. green).
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