Morphologic variability of human chromosomes: polymorphism of constitutive heterochromatin.

Polymorphism of constitutive heterochromatin has been studied in a series of 30 normal individuals. A high frequency of C-band variants were observed. Twenty-six of the 30 individuals studied had at least one polymorphic variant of the C band. A total of 42 variants were recorded which were predominately localized near the centromeric heterochromatin block of chromosome 9 (26.19%), chromosome 16 (19.05%), and chromosome 1 (16.66%). These results are discussed together with the findings revealed by different studies.