Distal monosomy 16p13.3/distal trisomy 2p24.2-pter: molecular-cytogenetic characterisation and phenotype.

We describe a 4-year-old boy with various facial dysmorphic features such as downslanting palpebral fissures, ptosis, hypertelorism, broad nasal bridge, small and low-set ears, broad philtrum, and micrognathia. In addition, profound mental retardation, myopia, muscular hypotonia as well as genital and cardiovascular abnormalities are also present. Refinement of the breakpoints by cytogenetic techniques, in particular the increase of banding resolution in conventional cytogenetic analysis, has enabled the correct diagnosis, as proven by fluorescence in situ hybridisation (FISH) using whole chromosome painting and single copy probes. We were able to demonstrate an unbalanced translocation that the patient inherited from his father resulting in a submicroscopic monosomy 16p13.3 and a trisomy 2p24.2-pter.