Phenotypic spectrum of interstitial 7p duplication in mosaic and non-mosaic forms

The phenotypes of a mother and child with a duplication of 7p15-7p22 are described. The mother is mosaic for the cytogenetic abnormality, whereas all cells are affected in her son. Fewer than 5 patients with interstitial 7p duplications are described in the world literature whereas over 30 phenotypic descriptions of individuals with terminal 7p duplication can be found. Authors have suggested that the associated phenotype amounts to a recognizable syndrome. The current cases give further insights into the phenotype that results from pure 7p duplication, both in its mosaic and in its full form. Comparisons are made with previous cases, in the light of the shorter segment involved in the current patients, whose duplication does not extend to pter. This case description will be useful in counseling patients with duplications of 7p and lends support to the existence of characteristic craniofacial features and congenital malformations in this chromosome rearrangement. In addition, as earlier case reports all describe the phenotype associated with non-mosaic partial 7p trisomy, the current observations amount to clear evidence that mosaicism attenuates the phenotype of this rearrangement.