Teratology (from the Greek τέρᾰς (genitive τέρᾰτος), meaning monster, or marvel and λόγος, meaning word, speech) as early as 17th century referred to a discourse on prodigies and marvels, of anything so extraordinary as to seem abnormal. In 19th century, it acquired a meaning closer related to biological deformities, mostly in the field of botany. Currently, its most instrumental meaning is that of the medical study of teratogenesis, congenital malformations or grossly deformed individuals. Monster is a pejorative term for a grossly deformed individual, although it is interesting to note that, etymologically, this word is related to demonstration, and used to simply mean something worth looking at, for being unusual, without necessarily being pejorative. Another term for this is dysmorphology, which literally means "the study of abnormal form." The genitive case is a grammatical case that indicates a relationship, primarily one of possession, between the noun in the genitive case and another noun. ... A congenital disorder is any medical condition that is present at birth. ... It has been suggested that this article or section be merged with pejoration. ...

Teratology as a medical term was popularized in the 1960s by Dr. David W. Smith of the University of Washington Medical School, one of the researchers who became known in 1973 for the discovery of Fetal alcohol syndrome.^{[citation needed]} With greater understanding of the origins of birth defects, the field of teratology now overlaps with other fields of medicine, including developmental biology, embryology, and genetics. The University of Washington, founded in 1861, is a public research university in Seattle, Washington. ... Fetal alcohol syndrome or FAS is a disorder of permanent birth defects that occurs in the offspring of women who drink alcohol during pregnancy. ... Views of a Foetus in the Womb, Leonardo da Vinci, ca. ... This article or section is in need of attention from an expert on the subject. ... This article is about the general scientific term. ...

Teratogenesis and teratology

Birth defects are known to occur in 3-5% of all newborns.^[1] They are the leading cause of infant mortality in the United States, accounting for more than 20% of all infant deaths. Seven to ten percent of all children will require extensive medical care to diagnose or treat a birth defect.^[2] Although significant progress has been made in identifying etiologic causes of some birth defects, approximately 65% have no known or identifiable cause.^[3]

It was previously believed that the mammalian embryo developed in the impervious uterus of the mother, protected from all extrinsic factors. However, after the thalidomide disaster of the 1960's, it became apparent and more accepted that the developing embryo could be highly vulnerable to certain environmental agents that have negligible or non-toxic effects to adult individuals. Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... For other uses, see Embryo (disambiguation). ... This article is about the drug. ... For other uses, see Embryo (disambiguation). ...

Wilson's 6 principles

Along with this new awareness of the in utero vulnerability of the developing mammalian embryo came the development and refinement of The Six Principles of Teratology which are still applied today. These principles of teratology were put forth by Jim Wilson in 1959 and in his monograph Environment and Birth Defects.^[4] It is these principles that guide the study and understanding of teratogenic agents and their effects on developing organisms In Utero is the third and final studio album by the American grunge band Nirvana, released on September 21, 1993 by Geffen Records (DGC). ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... For other uses, see Embryo (disambiguation). ...

• Susceptibility to teratogenesis depends on the genotype of the conceptus and the manner in which this interacts with adverse environmental factors.
• 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 access of adverse influences to developing tissues depends on the nature of the influence. Several factors affect the ability of a teratogen to contact a developing conceptus, such as the nature of the agent itself, route and degree of maternal exposure, rate of placental transfer and systemic absorption, and composition of the maternal and embryonic/fetal genotypes.
• There are four manifestations of deviant development (Death, Malformation, Growth Retardation and Functional Defect).
• Manifestations of deviant development increase in frequency and degree as dosage increases from the No Observable Adverse Effect Level (NOAEL) to a dose producing 100% Lethality (LD100).

Studies designed to test the teratogenic potential of environmental agents use animal model systems (e.g., rat, mouse, rabbit, dog, and monkey). Early teratologists exposed pregnant animals to environmental agents and observed the fetuses for gross visceral and skeletal abnormalities. While this is still part of the teratological evaluation procedures today, the field of Teratology is moving to a more molecular level, seeking the mechanism(s) of action by which these agents act. Genetically modified mice are commonly used for this purpose. In addition, pregnancy registries are large, prospective studies that monitor exposures women receive during their pregnancies and record the outcome of their births. These studies provide information about possible risks of medications or other exposures in human pregnancies. In science, a molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. ... Genetic engineering, genetic modification (GM), and gene splicing (once in widespread use but now deprecated) are terms for the process of manipulating genes in an organism, usually outside of the organisms normal reproductive process. ...

Understanding how a teratogen causes its effect is not only important in preventing congenital abnormalities but also has the potential for developing new therapeutic drugs safe for use with pregnant women. Teratogenesis is a medical term from the Greek, literally meaning monster making. ...

Teratology education

It is estimated that 10% of all birth defects are caused by a prenatal exposure or teratogen.^[3] These exposures include, but are not limited to, medication or drug exposures, maternal infections and diseases, and environmental and occupational exposures. Teratogen-caused birth defects are potentially preventable. Studies have shown that nearly 50% of pregnant women have been exposed to at least one medication during gestation.^[5] 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.^[6]

Teratogenic agents

A wide range of different chemicals and environmental factors are suspected or are known to be teratogenic in humans and in animals. A selected few include:

• Ionizing radiation: atomic weapons, radioiodine, radiation therapy

• Infections: cytomegalovirus, herpes virus, parvovirus B-19, rubella virus (German measles), syphilis, toxoplasmosis, Venezuelan equine encephalitis virus

• Metabolic imbalance: alcoholism, endemic cretinism, diabetes, folic acid deficiency, hyperthermia, phenylketonuria, rheumatic disease and congenital heart block, virilizing tumors

• Drugs and environmental chemicals: 13-cis-retinoic acid, isotretinoin (Accutane), aminopterin, androgenic hormones, busulfan, captopril, enalapril, chlorobiphenyls (PCBs), Dioxin, coumarin, cyclophosphamide, diethylstilbestrol, diphenylhydantoin (Phenytoin, Dilantin, Epanutin), ethanol, ethidium bromide, etretinate, lithium, methimazole, organic mercury, penicillamine, tetracyclines, thalidomide, trimethadione, uranium, methoxyethyl ethers and valproic acid.

The status of some of the above substances (e.g. diphenylhydantoin) is subject to debate, and many other compounds are under varying degrees of suspicion. These include Agent Orange,^[7] nicotine,^[8] aspirin and other NSAIDs. Other compounds are known as severe teratogens based on veterinary work and animal studies, but aren't listed above because they have not been studied in humans, e.g. cyclopamine. Teratogenic effects also help to determine the pregnancy category assigned by regulatory authorities; in the United States, a pregnancy category of X, D, or C may be assigned if teratogenic effects (or other risks in pregnancy) are documented or cannot be excluded. The mushroom cloud of the atomic bombing of Nagasaki, Japan, in 1945 lifted nuclear fallout some 18km (60,000 feet) above the epicenter. ... Radioiodine is the common name for iodine-131, a radioisotope of iodine. ... Varian Clinac 2100C Linear Accelerator Radiation therapy (or radiotherapy) is the medical use of ionizing radiation as part of cancer treatment to control malignant cells (not to be confused with radiology, the use of radiation in medical imaging and diagnosis). ... Species see text Cytomegalovirus (CMV) (from the Greek cyto-, cell, and -mega-, large) is a viral genus of the Herpesviruses group: in humans it is commonly known as human herpesvirus 5 (HHV-5). ... In colloquial use, herpes virus refers to the herpes simplex virus, particularly when transmitted sexually. ... Species Canine minute virus Canine parvovirus Chicken parvovirus Feline panleukopenia virus Feline parvovirus HB virus H-1 virus Kilham rat virus Lapine parvovirus LUIII virus Mice minute virus Mink enteritis virus Mouse parvovirus 1 Porcine parvovirus Raccoon parvovirus RT parvovirus Tumor virus X Parvovirus, commonly called parvo, is a genus... Rubella, commonly known as German measles, is a disease caused by the rubella virus. ... Syphilis is a sexually transmitted disease caused by Treponema pallidum. ... Venezuelan equine encephalitis virus is a mosquito-borne viral pathogen that causes Venezuelan equine encephalitis or encephalomyelitis (VEE). ... Alcoholism is the consumption of, or preoccupation with, alcoholic beverages to the extent that this behavior interferes with the drinkers normal personal, family, social, or work life, and may lead to physical or mental harm. ... Cretinism is a condition of severely stunted physical and mental growth due to untreated congenital deficiency of thyroid hormones (hypothyroidism). ... This article is about the disease that features high blood sugar. ... Signs of folic acid deficiency are often subtle. ... This article does not cite any references or sources. ... Phenylketonuria (PKU) is an autosomal recessive genetic disorder characterized by a deficiency in the enzyme phenylalanine hydroxylase (PAH). ... Rheumatology, a subspecialty of internal medicine, is devoted to the diagnosis and treatment of rheumatic diseases. ... A heart block is a disease in the electrical system of the heart. ... In biology and medicine, virilization refers to the development of changes which make a male body different from a female body. ... Retinoic acid, or Retin-A or vitamin A acid, is a carotenoid organic compound that is a component of visual pigments. ... Isotretinoin (INN) (IPA: ) is a medication used for the treatment of severe acne. ... Aminopterin (4-aminopteroic acid), a 4-amino analog of folic acid, is an antineoplastic drug with immunosuppressive properties used in chemotherapy. ... Androgen is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of masculine characteristics in vertebrates. ... Busulfan is a chemotherapy drug that is an alkylating agent (slows the growth of cancer cells). ... Captopril is an Angiotensin-Converting Enzyme inhibitor (ACE inhibitor) used for the treatment of hypertension and some types of chronic heart failure. ... Enalapril is an angiotensin converting enzyme (ACE) inhibitor used in the treatment of hypertension and some types of chronic heart failure. ... “PCB” redirects here. ... Dioxin is the common name for the group of compounds classified as polychlorinated dibenzodioxins (PCDDs). ... Coumarin is a chemical compound; a toxin found in many plants, notably in high concentration in the tonka bean, woodruff, and bison grass. ... Cyclophosphamide (the generic name for Cytoxan, Neosar) is a nitrogen mustard alkylating agent, used to treat various types of cancer and some autoimmune disorders. ... Diethylstilbestrol (DES) is a drug, a synthetic nonsteroidal estrogen that was first synthesized in 1938. ... Phenytoin sodium (marketed as Dilantin® in the USA and as Epanutin® in the UK, by Parke-Davis, now part of Pfizer) is a commonly used antiepileptic. ... Grain alcohol redirects here. ... R-phrases , S-phrases , , , , , Flash point > 100 °C Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Absorption spectrum of ethidium bromide Ethidium bromide (sometimes abbreviated as EtBr) is an intercalating agent commonly used as a nucleic... Etretinate (Tegison®) is a medication used to treat severe psoriasis. ... This article is about the chemical element named Lithium. ... Methimazole is an antithyroid drug similar in action to propylthiouracil. ... General Name, Symbol, Number mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12, 6, d Appearance silvery Standard atomic weight 200. ... Penicillamine is a pharmaceutical of the chelator class. ... This article deals with the specific Tetracycline antibiotic. ... This article is about the drug. ... Trimethadione is an oxazolidinedione anticonvulsant. ... General Name, symbol, number uranium, U, 92 Chemical series actinides Group, period, block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Standard atomic weight 238. ... Valproic acid (VPA) is a chemical compound that has found clinical use as an anticonvulsant and mood-stabilizing drug, primarily in the treatment of epilepsy and bipolar disorder. ... For other uses, see Agent Orange (disambiguation). ... This article is about the chemical compound. ... This article is about the drug. ... Non-steroidal anti-inflammatory drugs, usually abbreviated to NSAIDs, are drugs with analgesic, antipyretic and anti-inflammatory effects - they reduce pain, fever and inflammation. ... Cyclopamine (11-deoxojervine) is naturally-occurring chemical that belongs to the group of steroidal jerveratrum alkaloids. ... The pregnancy category of a pharmaceutical agent is an assessment of the risk of fetal injury due to the pharmaceutical, if it is used as directed by the mother during pregnancy. ...

Isotretinoin (13-cis-retinoic-acid; brand name Accutane), which is often used to treat severe acne, is such a strong teratogen that just a single dose taken by a pregnant woman may result in serious birth defects. Because of this effect, most countries have systems in place to ensure that it is not given to pregnant women, and that the patient is aware of how important it is to prevent pregnancy during and at least one month after treatment. Medical guidelines also suggest that pregnant women should limit vitamin A intake to about 700 μg/day, as it has teratogenic potential when consumed in excess.^[9][10] Isotretinoin (INN) (IPA: ) is a medication used for the treatment of severe acne. ... A congenital disorder is a medical condition or defect that is present at or before birth (for example, congenital heart disease). ... Vitamin A is an essential human nutrient. ... The international prototype, made of platinum-iridium, which is kept at the BIPM under conditions specified by the 1st CGPM in 1889. ...

Teratogenic outcomes

Exposure to teratogens can result in a wide range of structural abnormalities such as cleft lip, cleft palate, dysmelia, anencephaly, ventricular septal defect. In most cases, specific agents produce a specific teratogenic response. Dysmelia (from Greek Δύσ - = bad plus μέλος (plural μέλεα) = limb) is a congenital disorder referring to the limbs. ... This article does not cite any references or sources. ... A ventricular septal defect (or VSD) is a defect in the ventricular septum (the wall dividing the left and right ventricles of the heart). ...

See also

• Summa izbu - a set of Mesopotamian omen texts about Teratology.
• Congenital abnormalities
• Carcinogen
• Mutagen

Summa izbu is the ancient name for a set of ancient Mesopotamian omen writings based on teratology (the study of monstrous births). ... Mesopotamia was a cradle of civilization geographically located between the Tigris and Euphrates rivers, largely corresponding to modern-day Iraq. ... A congenital disorder is a medical condition that is present at birth. ... The hazard symbol for carcinogenic chemicals in the Globally Harmonized System. ... In biology, a mutagen (Latin, literally origin of change) is a physical or chemical agent that changes the genetic information (usually DNA) of an organism and thus increases the number of mutations above the natural background level. ...

External links

• Society of Teratology
• European Teratology Society
• Organization of Teratology Information Specialists
• March of Dimes Foundation
• A Telling of Wonders: Teratology in Western Medicine through 1800 (New York Academy of Medicine Historical Collections)

References