Atypical Sex Chromosome Patterns

• What is an atypical sex chromosome pattern?

  Any pattern deviating from XX or XY
• What is Klinefelter’s Syndrome?

  A condition affecting males with XXY pattern
• How common is Klinefelter’s Syndrome?

  Affects 1 in 600 males
• What is the chromosome count in Klinefelter’s Syndrome?

  47 chromosomes instead of 46
• What are the physical characteristics of Klinefelter’s Syndrome?

  • Reduced body hair
  • Breast development at puberty
  • Long, gangly limbs
  • Underdeveloped genitals
  • Coordination issues and clumsiness
  • More susceptible to female conditions
• What are the psychological characteristics of Klinefelter’s Syndrome?

  • Poorly developed language skills
  • Poorly developed reading ability
  • Passive and shy
  • Lack of interest in sexual activity
  • Struggles with memory
  • Struggles with problem-solving
• What is Turner’s Syndrome?

  A condition affecting females with XO pattern
• How common is Turner’s Syndrome?

  Affects 1 in 5000 females
• What is the chromosome count in Turner’s Syndrome?

  45 chromosomes instead of 46
• What are the physical characteristics of Turner’s Syndrome?

  • No menstrual cycle
  • Ovaries do not develop
  • Lack of breast development at puberty
  • Low set ears and webbed neck
  • High hip:waist ratio
  • Retain prepubescent appearance
• What are the psychological characteristics of Turner’s Syndrome?

  • Higher than average reading ability
  • Lower than average spatial memory
  • Lower than average visual memory
  • Lower than average mathematical performance
  • Socially immature
  • Trouble relating to peers
• What is the real-world application of research on Klinefelter’s Syndrome?

  • Leads to earlier diagnoses
  • More positive outcomes for individuals
  • Benefits for those treated from a young age
• What did the study of 87 individuals with Klinefelter’s Syndrome reveal?

  Early treatment leads to significant benefits
• How does the nature-nurture debate relate to atypical chromosome patterns?

  • Comparison shows psychological differences
  • Suggests biological basis for differences
  • Supports innate 'nature' influences on behavior
• Why is the relationship between atypical chromosomes and behavior not causal?

  Social treatment may influence behavior outcomes
• What is a sampling issue in studying Klinefelter’s and Turner’s syndrome?

  • Need large databases for accurate characteristics
  • Only severe symptoms are typically identified
  • Typical symptoms may be exaggerated
• How might the typical picture of Klinefelter’s and Turner’s syndrome be distorted?

  Only severe cases are usually identified
• What is a strength for Atypical Sex Chromosome Patterns?

  Real World Application

  • Continued research is likely to lead to earlier and more accurate diagnoses and is likely to lead to more positive outcomes in the future
  • 87 individuals with Klinefelter’s syndrome showed that those who had been identified and treated from a young age had significant benefits in terms of managing their syndrome, compared to those who had been diagnosed in adulthood
  • This suggests that increased awareness of atypical chromosome patterns does have a useful real-world application
• What is a strength for Atypical Sex Chromosome Patterns?

  Nature-Nurture Debate

  • By comparing people with these conditions with chromosome-typical people, it becomes possible to see psychological and behavioural differences between the two groups
  • It might be logically inferred that these differences have a biological basis and are a direct result of the abnormal chromosomal structure
  • This would support the view that innate ‘nature’ influences have a powerful effect on psychology and behaviour
• What is a limitation for Atypical Sex Chromosome Patterns?

  Not Causal

  • The relationship between the atypical chromosomes associated with Klinefelter’s and Turner’s syndrome and the differences in behaviour observed due to these conditions is not causal
  • Social immaturity seen in females with Turner’s syndrome may arise due to being treated immaturely, which may have an indirect impact upon their performance at school
  • This shows that it could be wrong to assume that psychological and behavioural differences in people with atypical sex chromosome patterns are due to nature
• What is a limitation for Atypical Sex Chromosome Patterns?

  Sampling Issue

  • In order to identify the characteristics of XXY and XO individuals, it is necessary to identify a large number of individuals with the disorder and build a database to see the full range of characteristics from mild to severe
  • In general, only those with the most severe symptoms are identified, and so the picture of typical symptoms may be distorted
  • This suggests that the typical picture of Klinefelter’s and Turner’s syndrome may well be exaggerated