case studies

• (1) Down's syndrome: 47, +21 (Trisomy 21)

  • extra chromosome 21
  • shortened life expectancy, slow cognition,, webbed neck, upward slanting eyes, flattened nose and face
• (2) Turner's syndrome: 45, X (Monosomy)

  • affects females only, one X chromosome only in each cell
  • affects growth and sexual development
  • females affected -> shorter than normal, fail to start puberty when they should (ovaries fail to develop properly)
• (3) Klinefelter syndrome: 47, XXY (Trisomy)

  • affects males only, one extra chromosome
  • at puberty, more breast tissue development than normal, less muscular body, little facial or body hair
  • sterile, cannot produce sperm
  • learning disabilties
• (4) Patau syndrome: 47, +13 (Trisomy 13)

  • affects infants, one extra chromosome 13
  • not mentally alert, thought to be deaf, have harelip and cleft palate, most organs malfunction
  • average survival of infants affected: 3 months