1. Congenital Anomalies and Teratogens
Structural, behavioral, functional and
metabolic disorders present at birth.
The science that studies these disorders
is teratology(畸形学).
BD - 2-3% at birth (live), 4-6% by 1 yr
~20% of infant deaths

2. Causes of Birth Defects
Genetic/Chromosomal %
Environmental (teratogens) %
Combined %
Multiple Gestations - 1%
Unknown %

3. 1.Genetic/ Chromosomal Causes
Down’s syndrome (21 trisomy)
Turner’s syndrome(45,X)
Microcephaly

4. 2.Environmental causes
Teratogens: agents that induce gross structural defects or “monsters”.
Physical agents：X-rays、hyperthemia
Chemical agents：heavy metals (mercury, lead),
alcohol，Cocaine
Infectious agents：virus, syphilis（梅毒）
Drugs and Hormones

5. Factors that influence the extent of disruption by the toxic agent include:
Exposure length
Timing of exopure (what stage of development)
Site targeted

6. Periods of Vulnerability
Preembryonic period Pregerm (0-2 wks)
Usually Death
Embryonic period Organogenesis (3-8 wks)
Abnormalities of Form (malformations)
Fetal period Growth/Maturation (9 wks – birth)
Growth Retardation
Mental dysfunction
Fetus vulnerable
Rapid cell proliferation
Cell migration
Cell differentiation

7. Current Methods of Diagnosis
UltraSound/Amniocentesis
Karyotyping
Spectral Karyotyping
FISH - translocation/target
PCR of target sequence
RT-PCR - gene expression

8. Ultrasound/Amnniocentesis (羊膜穿刺)

9. Detection of Chorion

10. Spectral Karyotyping All 23 chromosome pairs at one time
Different Fluorescent probes
Useful for translocations

11. Fluorescent In Situ Hybridization
Chromosome mapping
Identify and localize discrete chromosomal abnomalities
Deletions

12. Fluorescent In Situ Hybridization

13. PCR Using 2 small primers (20 bp) 25-40 cycles of: Denature Anneal
Synthesize
Identify gene expression or mutation