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Feature Article

Prenatal genetic screening and counselling

Robert Williamson, Robin Forbes

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Abstract

Many women in Australia are offered information early in pregnancy on the risks of a genetic disorder or chromosomal aneuploidy occurring in the fetus. The growing number of higher-risk pregnancies in older women and our increasing cultural diversity in Australia makes the provision of accurate advice both before and during pregnancy ever more important.

Key Points

  • An ultrasound scan acts as a preliminary test that could indicate an abnormality, such as Down syndrome or a cardiac defect.
  • Genetic screening is best carried out before pregnancy to allow time to offer the couple information, and time for them to discuss and think about the possible choices.
  • Most couples will choose to avoid having a child with a ‘serious disability’ either by using IVF to achieve pregnancy with pretested embryos or, if they find out their fetus is affected once pregnant, by terminating the pregnancy.
  • Cystic fibrosis and thalassaemia are the two recessive diseases for which there is a high existing level of awareness, and prenatal testing is often offered.
  • For most (but not every) dominant disease, a full clinical and family history will show if one of the parents is affected.
  • Down syndrome is the most common genetic disorder, with an increasing incidence with increasing maternal age.
  • The role of genetic counselling is, primarily, to provide accurate information and to let a couple know what medical options and other strategies they can legally use to deal with the situation they face.

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