How do malformations arise during embryonic development?

In biology, malformations arise from deviations in the normal course of embryonic development, particularly during the early stages of blastogenesis and organogenesis. These structural abnormalities are often linked to a reduction in the rate of development, with the specific nature of the deformity depending on the timing of this retardation.12

The causes of these developmental disruptions are diverse and frequently involve complex interactions between genetic and environmental factors:1

• Genetic Factors: These include gene mutations (Mendelian, recessive, or sex-linked) and chromosomal abnormalities, such as an unequal distribution of chromosomes during meiosis, which can lead to conditions like Down syndrome.34
• Environmental Factors: Teratogenic agents, including certain drugs, alcohol, infections, and irradiation, can interfere with embryonic cells.32
• Hormonal and Metabolic Factors: Deficiencies or excesses in fetal hormones and inborn errors of metabolism can disrupt normal chemical functioning and structural growth.32

The study of these deviations is known as teratology.13