Atypical Sex Chromosome Patterns

Question 1

what are the two syndrome that are due to atypical sex chromosomes?

Answer 1

• Klinefelter’s syndrome
• Turner’s syndrome

Question 2

what is Klinefelter’s syndrome?

Answer 2

• presence of an extra X chromosome : XXY
• affects 1 in 600 males
• 10% of cases can be identified by prenatal diagnosis
• 2/3s of people with KF are not aware of it

Question 3

what are the physical traits of Klinefelter’s syndrome?

Answer 3

• reduced body hair
• some breast development (gynecomastia)
• ‘softening’ or ‘rounding’ of body contours
• underdeveloped genitals
• problems with co-ordination and general clumsiness

Question 4

what are the psychological traits of Klinefelter’s syndrome?

Answer 4

• poorly developed language skills and reading ability
• passive and shy
• lack interest in sexual activity
• problems with executive functions such as memory and problem solving

Question 5

what is Turner’s syndrome?

Answer 5

• absences of an X chromosome: XO
• has 45 chromosomes rather than 46
• affects 1 in 5000 females

Question 6

what are the physical traits of Turner’s syndrome?

Answer 6

• don’t have a menstrual cycle (amenorrhoea)
• ovaries don’t develop so they are infertile
• do not develop breasts, have a broad ‘shield’ chest
• low set ears
• webbed neck
• short stature

Question 7

what are the psychological traits of Turner’s syndrome?

Answer 7

• higher than average reading ability
• spatial, visual memory and mathematical tasks are lower than average
• socially immature
• trouble relating to their peers and experience difficulty fitting in

Question 8

what are strengths of atypical sex chromosomes?

Answer 8

+ real world applications = earlier and accurate diagnosis, e.g. Herlihy et al = Aussie study with 87 individuals with KF showed that those who were diagnosed and treated at a very early age experiences significant benefits such as managing symptoms than those who were diagnosed in adulthood
+ contributions to nature-nurture debate, by comparing people with syndromes to chromosome-typical people we can see possible physical and behavioural differences. These differences have biological basis and is a direst result of abnormal chromosome patterns, so nature influences have an effect on behaviour and psychology

Question 9

what is a weakness of atypical sex chromosome pattens?

Answer 9

Point: One limitation with the description of Klinefelter’s syndrome is the potential sampling issue.
Evidence: For example, Boada (2009) reports that studies that followed XXY individuals from birth have shown that many do not experience significant cognitive or psychological problems.
Explain: This means that the characteristics of Klinefelter’s syndrome may be inaccurately represented as only those with severe symptoms were identified and studied.
Link: Therefore, this suggests that the typical picture of Klinefelter’s (and Turner’s syndrome) may well be exaggerated.