Expansion of a 12-kb VNTR containing the REXO1L1 gene cluster underlies the microscopically visible euchromatic variant of 8q21.2.

Copy number variants visible with the light microscope have been described as euchromatic variants (EVs) and EVs with extra G-light material at 8q21.2 have been reported only once before. We report four further patients with EVs of 8q21.

8p23.1 duplication syndrome differentiated from copy number variation of the defensin cluster at prenatal diagnosis in four new families.

Background: The 8p23.1 duplication syndrome and copy number variation of the 8p23.1 defensin gene cluster are cytogenetically indistinguishable but distinct at the molecular level.