title: Origin of extra chromosome in trisomy 21.
mesh_terms: D000328:Adult; D002648:Child; D002869:Chromosome Aberrations; D002904:Chromosomes, Human, 21-22 and Y; D004314:Down Syndrome / Q000235:genetics*; D005260:Female; D005453:Fluorescence; D006801:Humans; D007621:Karyotyping; D008297:Male; D008423:Maternal Age; D008540:Meiosis; D010641:Phenotype; D011110:Polymorphism, Genetic