High-resolution analyses of complex chromosome rearrangements (CCR) have 
demonstrated in individuals with abnormal phenotypes that not all seemingly 
balanced CCRs based on G-banding are completely balanced at breakpoint level. 
Here we report on an apparently balanced de novo CCR involving chromosomes 2, 3 
and 5 present in a 6-month-old girl. She was referred for genetic evaluation 
because of severe psychomotor retardation, distinctive dysmorphic features and 
microcephaly. A 1Mb resolution array-CGH analysis of DNA from the patient 
revealed a deletion of about 6Mb for chromosome 2. FISH analysis showed that the 
deletion interval found in band 2q22 mapped at the translocation breakpoint, and 
that the ZFHX1B gene, which is known to be involved in the Mowat-Wilson 
syndrome, is located within the deletion interval. To our knowledge this is the 
first case of a complex chromosomal rearrangement associated with Mowat-Wilson 
syndrome. Our data illustrate the important role for high-resolution 
investigation of apparently balanced chromosome rearrangements in patients with 
unexplained psychomotor retardation and/or other clinical features, and should 
contribute to our understanding of the mechanisms involved in chromosome 
rearrangement.