Down syndrome and mouse models.

The past year has seen major advancements in the characterisation of the Ts65Dn mouse model (which is now known to display many features of Down syndrome). A newer model that is trisomic for the region 21 q22.2--previously called 'Down syndrome' region--has been generated and these mice display behavioural and learning defects. Mutations in the genes Minibrain and SOD1 have been implicated in the development of learning defects in Down syndrome and many new genes from human chromosome 21 are being cloned, which should result in the genesis of other models that phenocopy one or more pathologies of the syndrome.