PARTIAL TRISOMY 13Q IDENTIFIED BY SEQUENTIAL FLUORESCENCE IN-SITU HYBRIDIZATION

We report on a 19-month-old boy with partial trisomy 13q resulting fro m a probable balanced translocation involving chromosomes 1 and 13. Th e infant presented with omphalocele, malrotation, microcephaly with ov erriding skull bones, micrognathia, apparently low-set ears, rocker-bo ttom feet, and congenital heart disease, findings suggestive of trisom y 13. Karyotypic studies from peripheral blood lymphocytes documented an unbalanced karyotype 46, XY, -1, + der(1). The mother's chromosomes were normal, and the father was not available. Conventional cytogenet ic techniques were unable to identify the extra material on the termin al Iq. Using fluorescence in situ hybridization (FISH) on the GTL-band ed metaphases, the extra material on Iq was identitied as the terminal long arm of 13, thus resulting in partial trisomy 13(q32-qter). (C) 1 995 Wiley-Liss, Inc.