CHARACTERIZATION OF A DE-NOVO UNBALANCED CHROMOSOME REARRANGEMENT BY COMPARATIVE GENOMIC HYBRIDIZATION AND FLUORESCENCE IN-SITU HYBRIDIZATION

Fluorescence in situ hybridization (FISH) has proven useful for the id entification of chromosomal material of unknown origin. More recently, comparative genomic hybridization (CGH) has been used to identify del etions and amplifications, particularly in neoplastic samples. Here, w e describe the combined use of CGH and FISH to identify the origin of a de novo unbalanced translocation in a newborn with multiple congenit al anomalies. GTG banding of metaphases from cultured lymphocytes show ed an unbalanced karyotype, with extra material on a chromosome 5:46,X X,add(5)(q35). Parental karyotypes were both normal. CGH revealed the additional material was from distal 11q (11q23 --> qter). This finding was confirmed by FISH with a whole chromosome paint for chromosome 11 . Based on the CGH and FISH analyses, the proband's karyotype was ther efore 46,XX,der(5)t(5;11)(q35.2;q23.2.ish der(5)(wcp11+). This case de monstrates the efficient use of CGH and confirmatory FISH for the iden tification of chromosomal material of unknown origin.