Atypical sex chromosome patterns

Question 1

What are atypical sex chromosome patterns?

Answer 1

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

Question 2

Outline Klinefelter’s syndrome

Answer 2

• an example of atypical sex chromosome pattern
• affects about 1 in 600 males
• individuals who have this condition are biological males and have an additional X chromosome (XXY)
• 10% of cases are identified by prenatal diagnosis
• around 2/3 of people who have Klinefelter’s syndrome are unaware of it
• diagnosis often comes about accidentally via a medical examination for some unrelated condition

Question 3

Outline the physical characteristics of Klinefelter’s syndrome

Answer 3

• tall, thin physique
• small, intertile testes
• enlarged breasts
• softening/rounding of body contours during puberty
• reduced facial hair
• clumsiness
• health issues more common in females (e.g. breast cancer)

Question 4

Outline the psychological characteristics of Klinefelter’s syndrome

Answer 4

• poorly developed language and reading skills
• passivity or shyness
• lack of interest in sexual activity
  difficulty managing stress
• issues with memory and problem solving

Question 5

Outline Turner’s syndrome

Answer 5

• it affects 1 in 5000 females
• caused by an absence of one of the two allotted X chromosomes - thus it is referred to as XO
• this means affected individuals have 45 chromosomes rather than the usual 46

Question 6

Outline the physical characteristic of \\turner’s syndrome

Answer 6

• no menstrual cycle (ovaries don’t develop)
• no breast development (instead they have a broad shielded chest)
• low set ears
• webbed neck (fold between neck and shoulders)
• hips and waist roughly same size

Question 7

Outline the psychological characteristics of Turner’s syndrome

Answer 7

• higher than average reading ability
• poor visual-spatial memory and mathematical ability
• ‘socially immature’
• do not fit in easily with peers

Question 8

Outline the nature-nurture debate as evaluation for atypical sex chromosome conditions

Answer 8

• strength of research into atypical sex chromosome conditions is its contribution to the nature-nurture debate
• by comparing characteristics of those with atypical chromosome patterns with those who have typical patterns, we can infer that any differences in psychological/physical characteristics are biological (nature
• e.g. those with Turner’s syndrome likely have better reading ability than others due to nature (XO) than nurture

Question 9

What is the counterpoint of the nature-nurture debate?

Answer 9

• assuming that the physical/psychological differences are due to nature also assumes causation
• can we be sure that having XXY causes clumsiness in men?
• does having XO cause social immaturity
• it could be that social/cultural factors are responsible for some characteristics
• e.g. those with Turner’s syndrome may be treated as immature in the first place or encouraged to behave in that way by parents

Question 10

Outline real life application as evaluation for atypical sex chromosome patterns

Answer 10

• research into atypical chromosome patterns increases insight into the syndromes associated, making diagnosis quicker and easier
• Herlihy et al. (2011) researched 87 male ppts with Klinefelter’s syndrome. They found that those diagnosed with Klinefelter’s syndrome at a very young age were significantly better at managing their condition compared to those diagnosed in adulthood
• furthermore, treatments have been developed to help manage symptoms - testosterone replacement therapy for those with Klinefelter’s , Oestrogen replacement therapy for those with Turner’s
• therefore developing our understanding has theoretical value, as well as real life and practical application

Question 11

Outline sampling issue as evaluation for Klinefelter’s syndrome

Answer 11

• in order to identify the characteristics of XXY (and XO) individuals, it’s necessary to identify a large number of individuals with the disorder and build a database
• in this way we can see the full range of characteristics from mild to severe
• in general only those who have the most severe symptoms are identified and therefore the picture of typical symptoms may be distorted
• Richard Boada et al. (2009) report that prospective studies (following XXY individuals from birth) have produced a more accurate picture of the characteristics - many individuals with Klinefelter’s do not experience significant cognitive or psychological problems, and many are highly successful academically, and in their personal lives and careers
• this suggests that the typical picture of Klinefelter’s may well be exaggerated