title: Bloodtyping and twin zygosity: reassessment and extension.
abstract: The determination of twin zygosity by bloodtyping is reconsidered, and the model for the individual case is reformulated. The crucial diagnostic question may be phrased as follows: Given the particular array of bloodgroup phenotypes that the twins display and are concordant for, how might this array have been obtained by a pair of dizygotic twins, and how might the array have been obtained by a monozygotic pair? The solution yields a differential probability value that is uniquely tailored to the actual phenotype array shown. The procedure offers a coherent and more direct method for arriving at the needed probability figures, and it is recommended to supersede previous methods. Some similarities and differences between the methods are discussed.
mesh_terms: D001788:Blood Grouping and Crossmatching; D005260:Female; D005819:Genetic Markers; D005821:Genetic Techniques; D006801:Humans; D008297:Male; D008433:Mathematics; D008957:Models, Genetic; D010641:Phenotype; D011247:Pregnancy; D011336:Probability; D014427:Twins
chemical_list: D005819:Genetic Markers