Use of DNA probe on c-some 9 heterochromatin

This shows a DNA probe which binds specifically to the heterochromatic region of human chromosome 9. Heterochromatic regions of chromosomes contain variable numbers of repeats, and are useful as polymorphic markers, allowing differentiation between the chromosomes of different individuals. This individual has a polymorphism in the heterochromatic region of chromosome 9 as one of the chromosome 9s has more repeats in this region, resulting in the extensive hybridisation signal seen on one chromosome 9.