title: [The thinking on the karyotypes of trisomy 21].
abstract: Different textbooks about medical genetics have different concepts of trisomy 21 and its karyotypes. On the basis of a great deal of information, the author of the present paper has been seriously thinking about it, and puts forward that there should be two karyotypes of trisomy 21, trisomy and mosaicism, and there should be three karyotypes in Down's syndrome, trisomy, mosaicism, and translocation.
authors.affiliation: Liaocheng Vocational and Technical College, Liaocheng, Shandong Province 252000, China. lcxywjy@163.com
authors.forename: Jing-Ying
authors.initials: JY
authors.lastname: Wang
mesh_terms: D004314:Down Syndrome / Q000235:genetics*; D006801:Humans; D007621:Karyotyping / Q000379:methods*