MOSAIC VS NONMOSAIC TRISOMY-9 - REPORT OF A LIVEBORN INFANT EVALUATEDBY FLUORESCENCE IN-SITU HYBRIDIZATION AND REVIEW OF THE LITERATURE

We report on a newborn infant with multiple congenital anomalies and a pparent nonmosaic trisomy 9 in the blood (by conventional cytogenetic studies) who died shortly after birth. Clinical observations at birth and autopsy are compared with phenotypes of mosaic and nonmosaic triso my 9 cases reported previously. Unlike the initial cytogenetic analysi s, fluorescence in situ hybridization (FISH) studies of metaphase and interphase blood cells and skin fibroblasts detected the presence of e uploid and trisomy 9 cells. These results suggest that earlier reports of trisomy 9, which relied on conventional chromosome analysis of a f ew metaphase cells and/or only one tissue type, may not have excluded mosaicism, and that trisomy 9 may be viable only in the mosaic state. (C) 1996 Wiley-Liss, Inc.