Microdissection-based high-resolution genomic array analysis of two patients with cytogenetically identical...

We describe two boys with cytogenetically identical interstitial deletions in the q42.11-q42.13 region of the long arm of chromosome 1 detected by high-resolution G-banding analysis. These children share some phenotypic features but also exhibit distinct morphologic differences. We further characterized the deletions using a new technical strategy--microdissection-based high-resolution genomic array (MHGA) analysis--to define the breakpoints, genomic sizes, and gene contents of the deletions. This showed that the patients had distinguishable deletions that were adjacent but did not overlap, thus explaining the observed phenotypic differences. These results were surprising because we expected at least some degree of overlap to explain the features that were shared. MHGA can quickly give precise and detailed information about any rearrangement in the genome using as little material as a single cell. This novel strategy provides unique advantages for both clinical diagnosis and genomic research.