Trisomy 20q caused by der(4) t(4;20) (q35;q13.1): report of a new patient and review of the literature.

An infant with multiple congenital anomalies and severe developmental delay was found to have a derivative chromosome 4 by routine karyotypic analysis. Using telomeric FISH analysis, the source of the additional chromatin was determined to be from 20q. The infant, thus, is trisomic for 20q13.1 to 20qter and monosomic for the sub-telomeric region of 4q. Other cases of trisomy 20q13.1to 20qter associated with telomeric deletions are reviewed and compared to the current patient. Copyright 2002 Wiley-Liss, Inc.