Antenatal and postnatal screening

• Monitoring the health of the mother, developing baby, and fetus


  A variety of techniques can be used
• Antenatal screening


  Identifies the risk of a disorder so that further tests and a prenatal diagnosis can be offered
• Antenatal screening tests


  • Ultrasound
  • Blood and Urine Tests
  • Diagnostic Testing
• Antenatal screening tests


  Two scans are given: Routine blood and urine tests, Dating scan (8-14 weeks), Amniocentesis, Anomaly scan (18-20 weeks), Chorionic villus sampling (CVS)
• Dating scans


  Determine stage and due date
• Chorionic villus sampling (CVS)


  Can be carried out earlier in pregnancy than amniocentesis, although it has a higher risk of misscarriage
• Anomaly scans


  May detect serious physical abnormalities in the fetus
• Cells from samples can be cultured to get enough cells to produce a karyotype to diagnose a range of conditions
• Postnatal screening


  Routine testing for metabolic disorders after birth
• In the UK, all newborn babies are routinely screened for Phenylketonuria (PKU)
• Phenylketonuria (PKU)


  A substitution mutation means that the enzyme which converts phenylalanine to tyrosine is non-functional. Individuals with high levels of phenylalanine are placed on a restricted diet
• Autosomes are any chromosome that isn't a sex chromosome
• Sex chromosome


  X and Y chromosome
• For a recessive trait to appear, both parents must be carriers
• For incomplete dominance, affected individuals must have two carrier parents
• Dominant traits appear in every generation
• Males are more affected by sex-linked disorders than females. Males cannot pass on linked disorders to their sons
• For females to be affected by sex-linked disorders, the father has to be affected and the mother a carrier
• Males and females are affected equally by dominant, recessive, and incomplete dominant traits