Identification of consistent novel submegabase deletions in low-grade oligodendrogliomas using array-based comparative genomic hybridization.

We have analyzed 18 low-grade gliomas using array comparative genomic hybridization (aCGH) with an average resolution of <500 kb. Because the majority of these tumors showed loss of chromosome arms 1p and 19q, we used custom statistical approaches to define submegabase hemizygous losses throughout the genome that correlated with 19q loss. As a result of this analysis, we have identified a approximately 550-kb region in 11q13 and a approximately 300-kb region in 13q12 that showed hemizygous deletion in virtually all the tumors analyzed regardless of their 1p/19q status. FISH analyses of interphase nuclei from the same tumors used for aCGH analysis confirmed the hemizygous loss. The identification of such specific changes provides a potentially very useful diagnostic marker for this subgroup of low-grade tumors. These regions of the genome define small numbers of candidate genes that are within the deletions. The aCGH analysis also defined the spectrum of gain and loss of genomic regions in low-grade oligodendrogliomas.