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Teratology is the study of abnormalities of physiological development in organisms during their life span. It is a sub-discipline in medical genetics which focuses on the classification of congenital abnormalities in dysmorphology caused by teratogens.
Teratogens are classified in four main categories: Drugs in pregnancy – in addition to environmental chemicals, includes recreational drug use and pharmaceutical drugs. Vertically transmitted infections; Radiation, such as X-rays; Mechanical forces, such as oligohydramnios; Teratogens affect the fetus by various mechanism including:
The effect of the developmental toxicants depends on the type of substance, dose, duration, and time of the exposure. The first few weeks of embryogenesis in humans is more susceptible to these agents. The embryogenesis is the most crucial time for the action of any teratogenic substances to result in birth defects.
Teratogens are substances that may cause birth defects via a toxic effect on an embryo or foetus. Wikimedia Commons has media related to Teratogens . See also the categories Carcinogens and Mutagens
During pregnancy, a woman can also be exposed to teratogens from contaminated clothing or toxins within the seminal fluid of a partner. [38] [30] [39] An additional study found that of 200 individuals referred for genetic counseling for a teratogenic exposure, 52% were exposed to more than one potential teratogen. [40]
Susceptibility to teratogenesis varies with the developmental stage at the time of exposure to an adverse influence. There are critical periods of susceptibility to agents and organ systems affected by these agents. Teratogenic agents act in specific ways on developing cells and tissues to initiate sequences of abnormal developmental events.
The thalidomide molecule is a synthetic derivative of glutamic acid and consists of a glutarimide ring and a phthaloyl ring (Figure 5). [15] [16] Its IUPAC name is 2-(2,6-dioxopiperidin-3-yl)isoindole-1,3-dione and it has one chiral center [15] After thalidomide's selective inhibition of TNF-α had been reported, a renewed effort was put in thalidomide's clinical development.
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