Published online by Cambridge University Press: 01 August 2014
Data obtained in a study of mentally defective twins permitted the examination of interdependence and efficiency of blood groups and fingerprints in zygosity diagnosis. After exclusion of Down's syndrome, the series consisted of 49 MZ pairs, 52 DZ pairs and 18 pairs of uncertain type.
Same-sex pairs discordant for Down's syndrome seemed to include some pairs of uniovular or irregular origin, but this could not be investigated cytologically. Concordance appeared to occur independently in different blood group systems. However, DZ twins concordant in the ABO blood groups were significantly more similar in their fingerprints than were other pairs, and the within-pair differences were more uniform.
Linear discriminant functions designed for zygosity diagnosis make much better use of dermatoglyphic information than do simpler measures, and the latter could not be much improved by comparing left and right hands separately.
The data used in this analysis were collected in a cooperative study undertaken by the Department of Medical Genetics of the New York State Psychiatric Institute and the National Institute of Mental Health. Franz J . Kallmann initiated the research and provided guidance until his death in 1965. The New York State Schools provided reports of twin admissions, facilities for examinations and, in some instances, laboratory tests.