Definition of trisomy-21 in English:

trisomy-21

noun

mass nounMedicine
  • The most common form of Down's syndrome, caused by an extra copy of chromosome number 21.

    • ‘Microcephaly can also be caused by the chromosomal disorder, trisomy-21 Down syndrome, and by environmental factors, such as fetal alcohol syndrome and fetal exposure to radiation before 15 weeks gestation.’
    • ‘The majority (about 94%) of children with Down Syndrome are born with standard Trisomy 21, which is not hereditary.’
    • ‘Trisomy 21 can be detected in the first few months of pregnancy by amniocentesis.’