Acrocentric chromosome polymorphisms: beware of cryptic translocations

Cryptic translocations may escape diagnosis, especially when they implicate chromosomal regions that are known to be polymorphic in the human karyotyp e. We describe a case of postnatal diagnosis of Beckwith-Wiedemann syndrome (BWS) due to an unbalanced translocation that had not been diagnosed in th e fetal karyotype. This first cytogenetic analysis revealed that one chromo some 14 presented as a common acrocentric short arm polymorphism. Further a nalyses after birth, using C-banding, NOR staining and fluorescence in situ hybridization (FISH) with telomeric probes, revealed that it was the resul t of an unbalanced de novo t(11;14)(p15;p13) translocation leading to parti al lip trisomy and to BWS. Prenatal cytogenetic management of such apparent ly inoffensive chromosome markers is discussed. Copyright (C) 2001 John Wil ey & Sons, Ltd.