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Atypical sex chromosome patterns - Coggle Diagram
Atypical sex chromosome patterns
Klinefelters syndrome is a genetic condition which affects 1 in 750 males and involves having an extra X chromosome (XXY). Was named after Dr Harold Klinefelter who reported the condition in 1942
Males with this have small testes that don't produce enough testosterone before birth and during puberty, which results in normal male characteristics not developing fully
Sufferers lack the ability to grow facial hair and pubic hair, develop breast tissue, have low muscularity and low fertility. There is also a tendency for long legs and arms in ration to the torso
Psychological effects include poor language skills which affects reading, quiet temperament, attention problems and increased anxiety and depression
Mosaic Klinefelters syndrome involves males having the extra X chromosome in only some of their cells. Sufferers tend to be less affected ( how affected depends on how many cells have the extra chromosome ). 1 in 10 KS sufferers are MKS sufferers
Very rarely males with KS can have several extra copies of the X chromosome or extra copies of both X and Y chromosomes. Symptoms are more severe in these cases
KS is not inherited by parents but occurs during meiosis. An error in cell division called nondisjunction causes an egg or sperm cell to have an extra X chromosome which leads to the embryo having an extra copy in each of its body cells ( a process called sex chromosome trisomy )
Medical complications can arise such as CVD, circulatory and respiratory conditions, as well as diabetes.
Older parents are more likely to have a child with KS and sufferers are generally treated with testosterone supplements - allowing them to live more normal lives but with a reduced lifespan
DeLisi - Subjected 11 KS participants and 11 non KS participants to psychiatric interviews, cognitive tests and MRI scans. 10 out of the KS males had psychiatric disturbance and generally they had smaller frontal lobes, temporal lobes and superior temporal gyrus brain areas - this may explain the language deficits and gives a biological basis to the problems experienced by them
Simpson - Behavioral and language issues from having KS could be treated with androgen therapy and psychological counselling. Detrimental effects of KS can be counteracted
Turners syndrome is a genetic condition that affects 1 in 2200 females. It is named after Dr Henry Turner who reported it in 1938. It involves having only 1 complete X chromosome in each cell, the second X chromosome is missing or incomplete
The condition occurs at conception but most of these conceptions lead to miscarriage (1 in 10 miscarriages in the first trimester are due to this)
Mosaic types of TS also exist where only 1 X chromosome is missing in some but not all cells
Prenatally lymphoedema occur where fluid leaks into tissues causing swelling, particularly in the neck, hands and feet. Physical effects that emerge after birth are short stature, down slanting eyes, a short webbed neck, broad chest and lots of moles and organ abnormalities - especially of the heart and kidneys
The main deficiency is non functioning ovaries which results in not developing breasts, not having periods and being infertile.
However 1/3 of girls with the condition have some typical changes during periods and 1/200 can get pregnant, have a normal vagina and uterus and enjoy a normal sex life
Medical complications can arise eg heart conditions, high blood pressure, urinary complaints, vision and hearing problems and osteoporosis
There are psychological problems with TS, aside from social adjustment due to physical appearance and a few girls having minor learning difficulties
It is rare to have a second child with TS
Treatment usually consists of giving growth hormones, as well as oestrogen and progesterone which allows sufferers to live a more normal life but with a reduced lifespan
Price - performed a study over 17 years of 156 females with TS finding that 15 died in that time compared with 3 deaths in the matched non TS females. This was due to cardiovascular and circulatory conditions
Brown - did MRI scans of 26 girls with TS and 26 gender and age matched girls without TS finding that girls with TS had smaller posterior cerebral and cerebellar brain areas. Suggests that TS affects growth of certain brain areas which may be related to the later developmental effects
Evaluation
The extraction of eggs from pre pubescent girls with TS offers a means of them later attaining pregnancy and the enhanced psychological benefits that would bring. However care must be taken to fully brief individuals about the technique and to gain consent
The comparison of people with typical and atypical chromosome patterns allow researchers to see what aspects of biological development and behaviour are under the influence of genetics and chromosomes
Research into patients with these syndromes has led to the development of therapies to improve the quality and duration of their lives
The effects of KS and TS originate from biology but some effects are environmental. Eg higher criminality is associated with males with KS but this may be through a lack of maturity through not achieving fatherhood or a long term partner
KS and TS can be diagnosed prenatally through cytogenetic analysis of a foetus but this can regarded as socially sensitive as this may put pressure on parents to have an abortion