We report the second case of a child with trisomy of the entire short arm of chromosome 17 secondary to a de novo duplication. Trisomy 17p in this patient resulted from a duplication, localized to the distal region of the long arm of the same chromosome, an abnormality not previously described. This cytogenetic abnormality was confirmed using whole chromosome paint, subtelomeric and Smith-Magenis probes by fluorescence in situ hybridization (FISH) analysis. The child presented with phenotypic features previously described in trisomy 17p, including some specific facial dysmorphia, microcephaly, growth retardation, hypotonia, short webbed neck, congenital heart defect, minor abnormalities of the hands, agenesis of the corpus callosum and abnormalities of the iris. Iris alterations and defects involving the left side of heart and the aorta also may represent truly clinical hallmarks of this cytogenetic abnormality. In conclusion, this cytogenetic anomaly seems to represent a severe malformation entity with a poor prognosis and a recognizable clinical pattern that justifies the use of the term "17p trisomy syndrome" suggested previously by other authors.