Frequently there are several unaligned sequences (inserts) in U95 sequences. Why?
The HG-U95 probes are selected from consensus sequences. Because the quality of the consensus sequence depends on the sequence information in the UniGene clusters, you may often see N's introduced in consensus sequences when the sequence information is either unavailable, or of low quality or complexity. These regions appear as unaligned sequences in the Probe Set Display image for HG-U95 sequences.