The sequences of the human chromosomes 21 and 22 indicate that there are approximately 770 well-characterized and predicted genes. In this study, empirically derived maps identifying active areas of RNA transcription on these chromosomes have been constructed with the use of cytosolic polyadenylated RNA obtained from 11 human cell lines. Oligonucleotide arrays containing probes spaced on averag...

Four new cases of ring G chromosomes are presented including one family in which the ring 21 is present in a mother and in her daughter, who has 47, XXX, r(21) chromosomes. The clinical and dermatoglyphic findings in r21 and r22 syndromes are reviewed.