title: A twin study of cytogenetic variability. Progress report.
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002503:Centromere; D002648:Child; D002877:Chromosomes, Human / Q000648:ultrastructure; D005260:Female; D005826:Genetics, Medical; D006801:Humans; D008213:Lymphocyte Activation; D008297:Male; D008940:Mitotic Index; D011247:Pregnancy; D012737:Sex Factors; D014427:Twins; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic