Genetic Disorder Detection

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Genetic Disorder Detection

• Genetic Screening
• Prenatal Diagnostic Testing

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Genetic Screening

• Examining a persons genetic make-up
• Used to determine whether a couple is at
  increased risk of having a baby with a hereditary
  genetic disorder.
• Genetic screening is not for everyone.
• Counseling is recommended when one or both
  partners know they have a genetic disorder or
  have family members who have or may have a
  genetic disorder

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Genetic Screening Cont.

• Family history assessment
• Carrier Screening
• testing people who do not have symptoms of a
  particular disorder but may have one autosomal
  recessive gene for that disorder and one normal
  gene

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Carrier Screening

• Screening is performed only if
• The disorder is very debilitating or lethal
• A reliable screening test is available
• One or both parents are likely to be a carrier
  because the disorder runs in the family or is
  common in their ethnic, racial, or geographic
  group
• The fetus can be treated, or reproductive options
  (such as abortion or elective sterilization) are
  available and acceptable to the parents.

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Carrier Screening

• In the United States, sickle cell anemia, the
  thalassemias, Tay-Sachs disease, and cystic
  fibrosis meet these criteria.
• Screening usually consists of analyzing a blood
  sample. Sometimes a sample of cells from the
  inside of the cheek is analyzed
• If carrier screening indicates that both parents
  have an autosomal recessive gene for the same
  disorder, the parents may decide to have prenatal
  diagnostic testing.

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Prenatal Diagnostic Testing

• Ultrasonography
• Chorionic Villus Sampling
• Amniocentesis
• Percutaneous umbilical blood sampling
• Information for first 5 slides from
  http//www.merck.com/mmhe/sec22/ch256/ch256a.html

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Chorionic Villus Sampling

• A doctor removes a small sample of the chorionic
  villi, which are tiny projections that make up
  part of the placenta
• Performed 10-12 weeks
• Results are available much earlier than
  amniocentesis

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Amniocentesis

• A sample of the fluid that surrounds the fetus
  (amniotic fluid) is removed
• Performed 14 weeks or later

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