Twins and Q-banded chromosome polymorphisms.

Q-banded chromosomal analyses were performed on 24 pairs of twins to determine the stability and heritability of chromosome polymorphisms, and to establish the use of these markers in the determination of twin zygosity. Sixteen twin pairs were determined monozygotic by chromosome polymorphism analysis and confirmed monozygotic by blood group genotyping. No two genetically distinct individuals had the same polymorphic pattern, suggesting the individuality of each morphological karyotype. The frequencies for the various types of chromosome polymorphisms, including stalk length variations, were determined. Analysis of frequency distribution for variant combinations showed random association.