Teratology

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Chemical structure of Thalidomide, a drug known for its teratogenic effects.

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Glossary

Teratology is the study of abnormalities of physiological development. It is often thought of as the study of birth defects, but it encompasses a broader range of developmental disorders that can occur during the embryonic or fetal stages of development. The term "teratology" is derived from the Greek word "teras," meaning "monster," reflecting the historical focus on gross anatomical abnormalities.

History

The field of teratology has evolved significantly over the centuries. Early studies were largely descriptive, focusing on the classification of congenital malformations. The modern scientific study of teratology began in the 20th century with the recognition of environmental factors that could cause birth defects, such as the infamous case of Thalidomide, a drug that caused limb defects in thousands of children when taken by pregnant women in the late 1950s and early 1960s.

Causes of Teratogenic Effects

Teratogenic effects can be caused by a variety of factors, including:

• Genetic factors: Mutations or chromosomal abnormalities can lead to congenital malformations.
• Environmental factors: Exposure to certain drugs, chemicals, or infections during pregnancy can result in teratogenic effects. For example, the use of Thalidomide during pregnancy led to severe limb deformities in newborns.
• Nutritional deficiencies: Lack of essential nutrients, such as folic acid, can lead to neural tube defects.

Mechanisms of Teratogenesis

The mechanisms by which teratogens cause developmental abnormalities are complex and can involve:

• Disruption of cell signaling pathways
• Interference with cell proliferation and differentiation
• Induction of cell death (apoptosis)

Examples of Teratogens

• Thalidomide: Originally marketed as a sedative, it caused severe limb deformities when taken during pregnancy.
• Alcohol: Consumption during pregnancy can lead to Fetal Alcohol Syndrome (FAS), characterized by growth deficiencies, facial abnormalities, and central nervous system dysfunction.
  

  A child with Fetal Alcohol Syndrome
• Rubella virus: Infection during pregnancy can lead to congenital rubella syndrome, causing heart defects, deafness, and cataracts.

Prevention and Management

Preventing teratogenic effects involves:

• Education: Informing women of childbearing age about the risks of certain drugs and substances during pregnancy.
• Screening and counseling: Genetic counseling and prenatal screening can help identify risks for congenital abnormalities.
• Nutritional support: Ensuring adequate intake of essential nutrients, such as folic acid, to prevent neural tube defects.

Research and Future Directions

Ongoing research in teratology aims to better understand the mechanisms of teratogenesis and to develop strategies for prevention and intervention. Advances in genomics and molecular biology are providing new insights into the genetic and environmental interactions that lead to developmental abnormalities.

Also see

• Congenital disorder
• Developmental biology
• Genetic counseling
• Prenatal diagnosis