De novo trisomy 16p.

We report on a patient with psychomotor retardation and a pattern of malformations comprising single umbilical artery, craniofacial anomalies, severe truncal hypotonia, and lower-limb hyporreflexia. G-banding cytogenetics demonstrated a 16p+ chromosome. Parental chromosomes were normal. The use of fluorescent in situ hybridization (FISH) showed that this extra material derived from chromosome 16. High-resolution G-banding demonstrated a duplicated segment on the 16p arm, confirming our suspicion of a de novo tandem duplication; hence, the cytogenetic diagnosis was given as 46,XY,dir dup(16)(p11.2-->p12).