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Edwards' syndrome

Background

Edwards syndrome: trisomy 18; 18+ syndrome

Edwards syndrome is a severe chromosome abnormality where the child has an extra chromosome 18 in every cell. A chromosome is a rod-like structure present in the nucleus of all body cells, with the exception of the red blood cells,and which stores genetic information. Normally humans have twenty-three pairs of chromosomes, the unfertilised ova and each sperm carrying a set of twenty-three chromosomes. On fertilisation the chromosomes combine to give a total of forty-six (twenty-three pairs). A normal female has an XX pair and a normal male an XY pair.

There are three types of the syndrome:-

  • Full form (severe) - in this every cell in the body has three chromosome 18's instead of two.
  • Mosaic form (less severe) - in this some cells have two chromosome 18's while others have three. The extent and severity of the condition will depend upon the ratio of normal to abnormal cells.
  • Partial form - in some cases there may be an extra copy of part of chromosome 18. This is referred to as partial trisomy 18. The effects of this may be milder and would require further medical advice.

Children with all their cells affected do not normally survive beyond infancy.T hose affected by the mosaic and partial forms may survive to adulthood.

What are the symptoms? View What are the symptoms?

Medical text written November 1991 by Contact a Family. Approved November 1991 by Professor M Patton, Professor of Medical Genetics, St Georges Hospital Medical School, London, UK and Dr J E Wraith, Consultant Paediatrician, Royal Manchester Children's Hospital, Manchester, UK. Last updated September 2003 by Contact a Family . Approved September 2003 by Professor I Young, Department of Clinical Genetics, Leicester Royal Infirmary, Leicester, UK.

 

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