Atypical chromosome patterns


Atypical sex chromosome patterns

Klinefelter's syndrome

  • Affects between 1/500 and 1/1000
  • People who have this condition are biological males but have an extra X chromosome
  • XXY
  • Physical characteristics:
    • Reduced body hair
    • Some breast development at puberty
    • Long, gangly limbs 
    • Underdeveloped genitals
    • Problems with co-ordination
  • Psychological characteristics
    • Poorly developed language skills
    • Passive, shy, lack libido
    • Exhibit problems with 'executive functions', memory and problem solving

Turner's syndrome

  • 1/5000 biological females 
  • Caused by an absence of one of two allotted X chromosomes
  • XO
  • Have 45 chromosomes, not 46
  • Physical charcteristics:
    • Do not have a menstrual cycle
    • Ovaries fail to develop, sterile
    • Do not develop breasts, broad chest
    • Low set ears and webbed neck
    • Physically immature and retain appearance of a pre-pubescent girl
  • Psychological characteristics
    • Higher than average reading ability
    • Performance on spatial, visual memory and maths tasks is lower than normal
    • Socially immature, have trouble…


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