Turner syndrome

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Turner Syndrome is a monosomic condition in which only one X chromosome is present (XO). This presents itself as 45,X in terms of karyotype.

Contents

Karyotype

Instead of having a set of 44 autosomes + 1 pair of sex chromosomes (either XX or XY) - the normal human karyotype, the person has only 44 autosomes + 1 X chromosomes. A person with Turner syndrome will have no barr bodies due to them only have 1 X chromosome.

Cause

Turner syndrome occurs as a result of nondisjunction, which is when chromosomes do not separate successfully during meiosis. It happens in about 1 in 2500 female births.

Phenotype

The affected person is phenotypically female but does not undergo sexual maturation[1]. This leads to poor breast development (with the nipples spread a distance apart)[2]. and the absence of menstruation[3]. Other phenotypes present include being short in stature, having a low hairline, a short and webbed neck and having small fingernails. These characteristics are present due to an obstruction of the lymphatic system during foetal development. Also, the constriction of the aorta is another phenotype of this syndrome. However, mental abilities are typically within the normal range[4]. Furthermore, different karyotypes found in patients with Turner Syndrome will manifest themselves as different phenotypes of the disease[5]. However, more than 99% of (Turner syndrome) fetuses undergo a spontaneous abortion. This indicates that the condition has profound deleterious effects on development[6].

Treatment

Currently, a cure for Turner syndrome has yet to be discovered. However, many of the associated symptoms can be treated. It is possible for a woman with this syndrome to live a healthy and normal life by maintaining regular health check-ups to identify and treat any health issues at early stages before any serious implications occur[7].

References

  1. Hartl D. L., Ruvolo M. (2012) Genetics Analysis of Genes and Genomes, Eighth edition(international edition), London: Jones and Bartlett Learning International. p273
  2. Anthony JF Griffiths et al., 1990, Modern Genetic Analysis, New York: W.H.Freeman, Chapter 8
  3. Puberty/Reproduction http://turners.nichd.nih.gov/clinical.html , January 2, 2012.
  4. Hartl D. L., Ruvolo M. (2012) Genetics Analysis of Genes and Genomes, Eighth edition(international edition), London: Jones and Bartlett Learning International. p273
  5. Al Alwan, Khadora M et.al. 2014. Turner Syndrome Genotype and phenotype and their effect on presenting features and timing of Diagnosis.(www.ncbi.nlm.nih.gov/pmc/articles/PMC4166992/) (22/10/2014)
  6. Hartl D. L., Ruvolo M. (2012) Genetics Analysis of Genes and Genomes, Eighth edition(international edition), London: Jones and Bartlett Learning International. p273
  7. Treatment http://www.nhs.uk/Conditions/Turners-syndrome/Pages/Introduction.aspx January 4, 2013.
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