Teratology

	Wendy Chung, MD PhD

Teratology

	The study of abnormal development in embryos and the causes of congenital malformations or birth defects

Birth Defects

	Observed in 3% of newborns
	Observed in another 3% of children later
	May or may not be outwardly visible
	Etiology: genetic and environmental

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Major and Minor Anomalies

	Major anomalies: life/health threatening
	Minor anomalies: cosmetic
	The greater the number of minor anomalies, the greater the likelihood of a major anomaly
	Certain minor anomalies suggest specific major anomalies

Down Syndrome

Turner Syndrome

Trisomy 13

	Midline defects (cleft lip and cleft palate)
	Central nervous system malformations
	Micro-ophthalmia
	Congenital heart disease
	Poor growth

Trisomy 18

Achondroplasia

Inborn Errors of Metabolism Causing Birth Defects

	Smith Lemli Opitz
	Congenital disorders of glycosylation
	Fatty acid oxidation disorders

Teratogens

	A chemical, infectious agent, physical condition, or deficiency that, on fetal exposure, can alter fetal morphology or subsequent function
	Teratogenicity depends upon the ability of the agent to cross the placenta
	The embryo is most susceptible to teratogenic agents during periods of rapid differentiation

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How are agents determined to be teratogenic ?

	Anecdotal data in humans
	Data from animal studies

Effect of Exposure Depends on Timing

	All or none effect early
	Effect of organogenesis during embryonic development
	Effect on size and function during fetal development

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Nicotine

	IUGR
	Premature delivery
	Neurocognitive development

Fetal Alcohol Syndrome

	Characteristic facial features
	Congenital heart disease
	Growth deficiency
	Behavioral/neurocognitive deficits

Fetal Alcohol Syndrome

Tetraclycine

	Yellow/brown teeth
	Decreased bone growth

Fetal Hydantoin Syndrome

	Intrauterine growth retardation
	Microcephaly, mental retardation
	Distal phalangeal hypoplasia
	Specific facial features

Retinoic acid

	Craniofacial dysmorphisms
	Cleft palate
	Thymic aplasia
	Neural tube defects

Thalidomide Syndrome

Congenital Rubella

Congenital CMV

	Intrauterine growth retardation
	Micromelia
	Chorioretinitis, blindness
	Microcephaly
	Cerebral calcifications, mental retardation
	Hepatosplenomegaly

Ionizing Radiation

	Affects brain development at 10-18 weeks of gestation a HIGH dose
	No evidence of effect of exposure associated with typical diagnostic studies

Maternal Hyperglycemia

	Congenital heart disease
	Renal, gastrointestinal, and central nervous system malformations such as neural tube defects

Babies of Mother’s with PKU

	Mental retardation
	Low birth weight
	Congenital heart diseas

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Threshold Effect-Multifactorial