I.down1[美 daʊn, 英 daʊn]副down often appears as the second element of certain verb structures in English (back down, clamp down, tone down, etc). For translations, see the relevant verb entry (back, clamp, tone, etc).
Down's syndrome patients seem to be protected from diabetic retinopathy due to an additional copy of chromosome 21, and elevated expression of endostatin.
Down's syndrome, which is caused by an extra copy of chromosome 21, is one of many abnormalities that result from such a failure of homologous recombination in meiosis.