Table 2.
Summary of the genomic analysis of the 21q11-21 region
| Genomic size of 21q11-21 | ∼20 Mb |
| Microdissection libraries specific for 21q11-21 | MA, MB, SA, SB |
| Independent, individual clones in the libraries | >40,000 (mean insert size 300 bp) |
| Cloned genomic size for 21q11-21 | >12 Mb |
| No. of microclones analyzed | >2,500 by repetitive sequence screening |
| >1,000 by Southern hybridization | |
| >400 (>120 kb DNA) by DNA sequencing | |
| Highly repetitive sequences in 21q11-21 | 46% |
| Moderately repetitive sequences in 21q11-21 | 24% |
| Low-copy sequences in 21q11-21 | 18% |
| Unique sequences specific for 21q11-21 | 12% |
| Methylation in 21q11-21 (HpaII sites) | >90% |
| Conserved microclones (cross-hybridizing to rodents) | 19% (76/400) in unique and low-copy microclones |
| GC content in unique and low-copy microclones | <40% |