Klinefelter's syndrome (Atypical sex chromosome patterns)

Question 1

What is Klinefelter’s syndrome?

Answer 1

A chromosomal conditions that affects males physical and cognitive development. Involves having an extra X chromosome giving males that have it the genetic makeup of XXY

Question 2

How many people does it affect?

Answer 2

1 in 750 males

Question 3

Who is the condition named after?

Answer 3

Dr Klinefelter who discovered the condition

Question 4

What do males born with the condition have?

Answer 4

Small testes that produce insufficient amounts of testosterone before birth and during puberty which results in normal sexual characteristics not developing fully

Question 5

What are the typical effects on sufferers?

Answer 5

Lack the ability to grow facial and pubic hair, develop breast tissue, have low muscularity and low fertility levels. Also a tendency to have long arms and legs in relation to the torso

Question 6

What are the psychological problems?

Answer 6

Poor language skills which affects reading ability, noticeably passive temperament, attention problems and increased risk of anxiety disorders and depression

Question 7

What is Mosaic Klinefelter’s syndrome (MKS)?

Answer 7

Involves males having the extra X chromosome in only some of their cells - sufferers tend to be less affected than those with KS

Question 8

Since not inherited how does KS occur?

Answer 8

During meiosis, the process of cell division that produces egg and sperm cell. An error in division called nondisjunction causes an egg or sperm cell to produce an extra copy of the X chromosome, leading to the embryo produced at conception having an extra copy of the X chromosome in each of its body cells (process known as sex chromosomes trisomy)

Question 9

How does MKS occur?

Answer 9

Similarly to KS, problems with cell divisions during early development in the womb leads to some body cells having an extra copy of the X chromosome

Question 10

What medical complications can arise from KS?

Answer 10

Cardiovascular, circulatory and respiratory conditions as well as diabetes and renal problems

Question 11

Who are more likely to have children with KS?

Answer 11

Older parents

Question 12

How are sufferers often treated and what is the effect if this?

Answer 12

Treated with testosterone supplements allowing them to live relatively normal lives, though with a below average lifespan

Question 13

What was Simpson’s research?

Answer 13

Found that behavioural and language difficulties resulting from having KS could be successfully treated with androgen therapy such as testosterone supplements and psychological counselling with greater improvement seen the earlier the treatment was given. Supporting the idea that some of the detrimental effects of KS can be successfully counteracted

Question 14

What was Swerdlow et al’s research?

Answer 14

Investigated mortality in men with KS between 1959 and 2003 in the UK and found that 461 of 3518 had died which was higher than similar non KS patients. Major causes of death were from cardiovascular and respiratory diseases as well as diabetes, renal failure and epilepsy which suggests KS patient have raised mortality rated due to hormonal and genetic mechanisms

Question 15

What was DeLisi et al’s research?

Answer 15

Subjected 11 KS patients and 11 non-KS patients to a psychiatric interview, cognitive tests and an MRI scan. Ten of the KS males had some form of psychiatric disturbance and generally KS sufferers had smaller frontal lobes, temporal lobes and superior temporal gyrus brain areas which may explain the language deficits noted in KS patients. This suggests that there is a biological basis for some of the psychological affects of KS

Question 16

What was Stochholm et al’s research?

Answer 16

Investigated criminal patterns in 1005 Danish men with standard KS and found that men with KS had higher conviction rates for sexual abuse, burglary, arson and lower conviction rated for traffic and drug offences than males without KS. However when adjustments were made for socioeconomic variables such as class these conviction levels were similar (apart from sexual abuse and arson) suggesting that KS’s association with criminality may be due to the poor conditions endured by sufferers rather than the condition itself

Question 17

In Stochholm’s research what may high criminality be due to?

Answer 17

A lack of maturity through not having relationships or achieving fatherhood to some extent, although KS is caused by the biological influences of genes and chromosomes there may be some impact of the environment on sufferers.

Question 18

What does the comparison between those with typical and those with atypical chromosome patterns allow us to see?

Answer 18

What is due to genetics and chromosomes and what isn’t