Knowledge of the complete genomic DNA sequence of an organism allows a syst
ematic approach to defining its genetic components. The genomic sequence pr
ovides access to the complete structures of all genes, including those with
out known function, their control elements, and, by inference, the proteins
they encode, as well as all other biologically important sequences. Furthe
rmore, the sequence is a rich and permanent source of information for the d
esign of further biological studies of the organism and for the study of ev
olution through cross-species sequence comparison. The power of this approa
ch has been amply demonstrated by the determination of the sequences of a n
umber of microbial and model organisms, The next step is to obtain the comp
lete sequence of the entire human genome. Here we report the sequence of th
e euchromatic part of human chromosome 22. The sequence obtained consists o
f 12 contiguous segments spanning 33.4 megabases, contains at least 545 gen
es and 134 pseudogenes, and provides the first view of the complex chromoso
mal landscapes that will be found in the rest of the genome.