De novo complete trisomy 5p: Clinical report and FISH studies

We describe a de novo trisomy 5p in a 1-year-old severely retarded boy. The complete short arm of chromosome 5 segregated as an additional marker chro mosome in all metaphases. The marker was identified as 5p by conventional c ytogenetic techniques (GTG, GBG, CBG) and molecular cytogenetic techniques (whole chromosome-painting probe, probes for the cri-du-chat region and the centromere, and additionally high-resolution multicolor banding using a ch romosome 5-specific DNA probe cocktail). The clinical findings were similar to the established trisomy 5p phenotype including macrocephaly, facial abn ormalities, tracheobronchial defects with subsequent respiratory infections , hypotonia, and psy chomotor retardation. To the best of our knowledge thi s is the first description of an isolated complete 5p trisomy without invol vement of the aberrant chromosome in any structural chromosomal rearrangeme nts. (C) 1999 Wiley-Liss, Inc.