Atypical Sex Chromosome Patterns

• Atypical Sex Chromosome Patterns

  Defined as any sex chromosome pattern that deviates from the usual XX/XY formation and which tends to be associated with a distinct pattern of physical and psychological symptoms.
• Klinefelter's Syndrome


  • Affects males in which the individuals' genotype has an extra X chromosome making them XXY
  • It affects in between 1 in 500 and 1 in 1000 people
  • In 10% of cases of this syndrome it is detected prenatally however 2/3 of sufferers are unaware they have the condition.
• Klinefelter's Syndrome: Characteristics


  • Physical characteristics: reduced body hair, breast development, underdeveloped genitals and small infertile testes
  • Psychological characteristics: poorly developed lang skills and poor reading ability, passive + shy, lack interest in sexual activity, and may exhibit problems with memory
• Turner's Syndrome


  • A chromosomal disorder in which affected females only have 1 X chromosome meaning they have 45 chromosomes rather than the usual 46.
  • It affects approximately 1 in 5000 women
• Turner's Syndrome: Characteristics


  • Physical characteristics: no menstrual cycle (amenorrhea), infertile, no breasts instead a broad 'shield' like chest, low set ears and 'webbed' neck and physically immature (low hip to waist ratio)
  • Psychological characteristics: higher than average reading ability, lower than average performance on spatial, visual memory and maths tasks, socially immature and trouble fitting in and relating.
• Evaluations: Nature-Nurture


  • Studies of people with atypical sex chromosome patterns are useful as they contribute to our understanding of the nature nurture debate.
  • By comparing people who have these conditions to individuals who are chromosomally-typical it is possible to assess the psychological and behavioural differences between the 2 groups.
  • It might be logical to infer that these differences are a direct result of the abnormal chromosomal structure and that these differences have a biological basis.
  • Such conclusions would suggest that innate influences have a powerful effect.
• Evaluation: Reductionism


  • However, to leap to this conclusion would be taking a biologically reductionist view. - The relationship between chromosomal abnormalities associated with Klinefelter's and Turner's syndrome and the differences seen in behaviour is not causal.
  • It might be that environmental and social influences may play a role.
  • For example, the social immaturity seen in females with Turner's syndrome may be a result of the fact that they were treated immaturely because they still appear childlike.
  • Therefore, it would be incorrect to assume that the observed psychological and behavioural differences are purely a product of biology.
• Evaluation: Practical Applications

  • Continued research into atypical sex chromosome patterns is likely to lead to earlier and more accurate diagnosis of such disorders as well as increasing positive future outcomes.
  • Herihly et al's (2011) study of 87 individuals with Klinefelter's showed that those who were identified and treated at a young age had significant benefits compared to those who had been diagnosed in adulthood.
• Evaluation: Sample


  Caution should be taken when drawing conclusions concerning gender development from such an unusual and unrepresentative sample.

  • As this group of people have atypical chromosomal patterns it is unlikely their gender development is representative of everyone and therefore, findings can be criticised for lacking generalisability