Trisomy 13

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Trisomy 13 is a genetic condition where the indiviual inhereits an extra copy of chromosome 13. It is also known as patau syndrome and affects around 1 in every 10,000 births. Over 80% of babies born with the condition will die before their first birthday.

The extra genetic material leads to many develeopmental problems. Symptoms can include: cleft lip and palate, seizures, congenital heart disease, decreased muscle tone, severe intellectual disability, low set ears and extra fingers or toes. 

A Diploid organism that has an extra copy of Chromosome 13 compared to the wildtype. It is Aneuploidy which means it does not have an exact multiple of the Haploid number. It is formed by the Nondisjunction of the chromosome 13 during Meiosis.  A trivalent or Bivalent and univalent is formed on Chiasma of the Homologous chromosomes during pachytene in Meiosis prophase 1. This condition is known as Patau Syndrome and results in only 17/85000 live births because, as most chromosome abnormailities do, results in spontaneous abortion. If one parent with the condition has offspring with a normal partner the offprings chances of also having the trisomy are 50%[1]. The people with this condition suffer from severe mental and physical develpmental problems including polydactyl (extra digits) and congenital heart defects. The mean life expectancy is just days old as it is such a severe genetic abnormality[2][3].


  1. Hartl, Ruvolo (2012) Genetics analysis of genes and genomes. 8th edition. p268-. Burlington. Jones and Barlett learning.
  2. Locock L, Crawford J, Crawford J (2005) The parents' journey: continuing a pregnancy after a diagnosis of Patau's syndrome. [INTERNET]BMJ. 19;331(7526):1186-9. (accessed 28/11/2013)
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