Final - Prenatal Diagnosis and Counseling

Question 1

Genetic counseling

Answer 1

• a communication process that has as its goal, the alleviation of human suffering associated with the occurrence, or risk of occurrence, of a genetic disorder in a family.

Question 2

Goals of genetic counseling

Answer 2

• is to help individuals and families to:
  1. comprehend the diagnosis, probable course of the disorder, and available management
  2. appreciate the way heredity and environment contribute to the disorder and the disorder’s risk of recurrence.
  3. understand the alternatives for dealing with the risk of recurrence
  4. choose the option which seems appropriate in view of the risks and their values and act in accordance with that decision
  5. make an optimal adjustment to the disorder in an affected family member and/or to the risk of recurrence of the disorder

Question 3

Basic steps of genetic counseling

Answer 3

1. Obtain medical and family histories
2. Ascertain mode of inheritance
3. Calculate risk of recurrence
4. Present and discuss options for dealing with the risk of recurrence
5. assist patient in arriving at decision
6. Management based on patient’s decision
7. Follow-up as needed

Question 4

Indications for referring patients to genetic counseling

Answer 4

1. Advanced maternal age (35 yo or older at time of delivery)
2. Family history of birth defects, mental retardation, or hereditary disorders
3. To obtain information or to have testing for genetic disorders hat occur more frequently in certain ethnic group
4. Consanguinity (First cousins or closer)
5. Advanced paternal age (starts at age 40)
6. Women who have had two or more miscarriages or babies who have died in infancy
7. Couples whose child has a genetic disease diagnosed by routine newborn screening
8. Women who have had abnormal prenatal screening tests, including maternal serum marker screening and sonograms

Question 5

Chronic Villus Sampling (CVS)

Answer 5

• prenatal diagnosis
• a procedure to remove a small piece of the placenta for the purpose of cytogenetic analysis or testing for particular genetic disorders

Question 6

Amniocentesis

Answer 6

• prenatal diagnosis
• involves removing amniotic fluid which contains shed cells from the baby and are used for cytogenetic analysis or DNA testing

Question 7

CVS vs. Amniocentesis:

CVS

Answer 7

Timing: 10-13.9 weeks
Loss or Complication Rate: at most 1%
Accuracy: 99.9%
Information tested: chromosomes
Turnaround Time: 2 weeks

Question 8

CVS vs. Amniocentesis:

Amniocentesis

Answer 8

Timing: 16+ weeks
Loss or Complication Rate: at most 0.33%
Accuracy: 99.9%
Information tested: chromosomes and spina bifida
Turnaround Time: 2 weeks

Question 9

Quad screening

Answer 9

• prenatal screening
• calculate the probability of women’s risk for having a child with Down Syndrome, Trisomy 18, or Spina Bifida, in order to identify and offer diagnostic testing to these patients
• second trimester Quad screening measures levels of 4 markers found in pregnant women’s blood but was produced by fetus or placenta.

Question 10

Markers for Open Spina Bifida

Answer 10

• Very high levels of AFP (4x higher than normal)

Question 11

Markers for Down Syndrome

Answer 11

• Low levels of AFP (25% lower than normal)
• low levels of uE3
• high levels of hCG and DIA

Question 12

Non-invasive Prenatal Testing

Answer 12

• a screening blood test that can measure fetal DNA in maternal circulation
• can be performed on women at or after 10 weeks gestation
• helps to identify risk for Down Syndrome (trisomy 21) (99%), trisomy 18 (99%), trisomy 13 (99%), Turner syndrome (95%), and Klinefelter syndrome (95%)
• *Not intended to replace diagnostic prenatal testing