De novo duplication of 12pter → p12.1: clinical and cytogenetic diagnosis confirmed by chromosome painting

A 12.5-year-old male patient with a de novo derivative chromosome 22 is reported. A detailed description of the clinical features and comparison with the results of conventional cytogenetic banding methods indicated that the derivative chromosome might have been caused by a translocation between the short arms of chromosomes 12 and 22: der(22)t(12;22)(p12.1;p11.2). Fluorescence in situ hybridization with a chromosome 12-specific paint confirmed this supposition. The patient thus carries a pure duplication of 12pter-->p12.1. The phenotype of the patient described is compared to cases in the literature.