Euchromatic 9q13-q21 duplication variants are tandem segmental amplifications of sequence reciprocal to 9q13-q21 deletions.

Background: There are four known pericentromeric euchromatic variants of chromosome 9 in the literature that are increasingly being observed in diagnostic cytogenetic laboratories. These variants pose diagnostic and counselling dilemmas, especially in prenatal settings, as distinction of a pathogenic alteration from a euchromatic variant is difficult. The molecular characterisation of three of these four variants has been reported.