NationMaster - Encyclopedia: Congenital defect

A congenital disorder is a medical condition that is present at birth. A congenital disorder can be recognized before birth (prenatally), at birth, or many years later. Congenital disorders can be a result of genetic abnormalities, the intrauterine environment, or unknown factors. A congenital condition can arise from the genetic make-up of the fertilized egg or be acquired at any time during fetal development. The causes of many congenital disorders are not known. Newborn with suctioning and umbilical cord Childbirth (also called labour, birth, or parturition) is the culmination of pregnancy, the emergence of a child from its mothers uterus. ... Genetics (from the Greek genno γεννώ= give birth) is the science of genes, heredity, and the variation of organisms. ... A zygote (Greek: ζυγωτόν) is a cell that is the result of fertilization. ... Embryogenesis is the process by which the embryo is formed and develops. ...

Congenital disorders include minor physical anomalies (e.g., a birthmark), severe malformations of single systems (e.g., congenital heart disease or amelia of the legs), and combinations of abnormalities affecting several parts of the body. Defects of metabolism are also considered congenital disorders. A congenital disorder can have trivial or grave effects. The most severe, such as anencephaly, are incompatible with life. A birthmark, is a blemish on the skin formed before birth. ... There are different forms of heart disease: Coronary heart disease Ischaemic heart disease Cardiovascular disease The study of heart disease is Cardiology This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Amelia is the birth defect of lacking one or more limbs. ... Cephalic disorders are congenital conditions that stem from damage to, or abnormal development of, the budding nervous system. ...

About 2-3% of babies are born with significant congenital birth defects. By organ system, birth defects involving the brain are the largest group at 10 per 1000 live births), compared to heart at 8 per 1000, kidneys at 4 per 1000, and limbs at 2 per 1000. All other defects have a combined incidence of 6 per 1000 live births. In the anatomy of animals, the brain, or encephalon, is the supervisory center of the nervous system. ... The heart (Latin cor) is a hollow, muscular organ that pumps blood through the blood vessels by repeated, rhythmic contractions. ... Kidneys viewed from behind with spine removed The kidneys are bean-shaped excretory organs in vertebrates. ... A limb (from the Old English lim) is a jointed appendage of the human or animal body; a large or main branch of a tree; a representative, branch or member of a group or organization. ...

About 25% of birth defects result from genetic abnormalities. About 5% involve abnormalities of large portions or entire chromosomes. Some congenital disorders arise from inheritance of abnormal genes from the parents but some can arise from a new mutation in one of the germ cells that contributed to the fetus. Genetics (from the Greek genno γεννώ= give birth) is the science of genes, heredity, and the variation of organisms. ... Figure 1: Chromosome. ... For the scientific journal Heredity see Heredity (journal) Heredity (the adjective is hereditary) is the transfer of characters from parent to offspring, either through their genes or through the social institution called inheritance (for example, a title of nobility is passed from individual to individual according to relevant customs and... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ... Mutations are permanent, sometimes transmissible (if the change is to a germ cell) changes to the genetic material (usually DNA or RNA) of a cell. ... Gametes (in Greek: γαμέτες) —also known as sex cells, germ cells, or spores—are the specialized cells that come together during fertilization (conception) in organisms that reproduce sexually. ...

Influences of the intrauterine environment of the fetus which can cause birth defects are referred to as teratogenic. These can include dietary deficiencies, toxic effects, or infections. For example, dietary deficiency of maternal folic acid is associated with spina bifida. Exposure to harmful substances during pregnancy (e.g, mercury) or maternal drugs (e.g., phenytoin) can cause recognizable combinations of birth defects. Many infections (e.g., rubella, syphilis), which a mother can contract during pregnancy can affect the baby. Teratogenesis is a medical term from the Greek, literally meaning monster making. ... Folic acid (the anion form is called folate) is a B-complex vitamin (once called vitamin M) that is important in preventing neural tube defects (NTDs) in the developing human fetus. ... General Name, Symbol, Number Mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12 (IIB), 6, d Density, Hardness liquid 13,579 kg/m3 solid @ âˆ’39 Â°C 15,600 kg/m3 1. ... 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. ... Rubella (also known as epidemic roseola, German measles or three-day measles) is a disease caused by the Rubella virus. ... Depression-era U.S. poster advocating early syphilis treatment Syphilis (historically called lues) is a sexually transmitted disease (STD) that is caused by a spirochaete bacterium, Treponema pallidum. ...

A significant proportion of birth defects cannot be attributed to either genetic abnormalities or environmental exposures. These are referred to as sporadic birth defects, a term which implies an unknown cause, random occurrence, and and a low recurrence risk for future children.

Terminology

Congenital disorders is a broad category that includes a variety of conditions. The following terms are used for various subsets of congenital disorders.

Birth defect is a widely-used term for a structural malformation of a body part, recognizable at birth, which is significant enough to be perceived as a problem.

A congenital physical anomaly is a difference, an abnormality, of the structure of a body part. An anomaly may or may not be perceived as a problem condition. Many people, if examined carefully, have minor physical anomaly. Examples of minor anomalies can include curvature of the 5th finger (clinodactyly), tiny indentations of the skin near the ears (preauricular pits), shortness of the 4th metacarpal or metatarsal bones, or dimples over the lower spine (sacral dimples). Some minor anomalies may be clues to more significant internal abnormalities.

A congenital malformation is a deleterious physical anomaly, a structural defect perceived as a problem. A recognizable combination of malformations or problems affecting more than one body part is referred to as a malformation syndrome. In medicine, the term syndrome is the association of several clinically recognizable features, signs, symptoms, phenomena or characteristics which often occur together, so that the presence of one feature alerts the physician to the presence of the others. ...

Genetic diseases or disorders are all congenital, though they may not be expressed or recognized until later in life. Genetic diseases may be divided into single-gene defects, multiple gene disorders, or chromosomal defects. Single-gene defects may arise from abnormalities of both copies of an autosomal gene (a recessive disorder) or of only one of the two copies (a dominant disorder). Some conditions result from deletions or abnormalities of a few genes located contiguously on a chromosome. Chromosomal disorders involve the loss or duplication of larger portions of a chromosome (or an entire chromosome) containing hundreds of genes. Large chromosomal abnormalities always produce effects on many different body parts and organ systems. A genetic disorder, or genetic disease is a disease caused, at least in part, by the genes of the person with the disease. ... An autosome is a non-sex chromosome. ... In genetics, the term recessive gene refers to an allele that causes a phenotype (visible or detectable characteristic) that is only seen in a homozygous genotype (an organism that has two copies of the same allele). ... The word dominant has several possible meanings: In music theory, the dominant or dominant note (second most important) of a key is that which is a perfect fifth above the tonic; in just intonation the note whose pitch is 1. ...

A congenital metabolic disease is also referred to as an inborn error of metabolism. Most of these are single gene defects, usually inheritable. Many affect the structure of body parts but some simply affect the function. Inborn errors of metabolism comprise a large class of genetic diseases involving disorders of metabolism. ...

Finally note that congenital conditions can be referred to as diseases, defects, disorders, anomalies, or simply genetic differences. The usage overlaps, but also involves a value judgement as to the harmfulness of the condition. See human variability and disease for more on the occasional difficulties of drawing these distinctions. Human variability, or human variation, refers to the range of possible values for any measurable characteristic, physical or mental, of human beings. ... A disease is any abnormal condition of the body or mind that causes discomfort, dysfunction, or distress to the person affected or those in contact with the person. ...

Risk of birth defects throughout gestation

The greatest risk of a malformation occurring is between the third and eighth week of gestation. Before this time, any damage to the embryo is likely to result in fatality and the baby will not be born. After eight weeks, the fetus and its organs are more developed, and is less sensitive to teratogenic incidents. A pregnant woman Pregnancy is the process by which a mammalian female carries a live offspring from conception until it develops to the point where the offspring is capable of living outside the womb. ... Embryos (and one tadpole) of the wrinkled frog (Rana rugosa you beezie). ...

The type of birth defect is also related to the time of exposure to a teratogen. For instance the heart is susceptible from three to eight weeks, but the ear is susceptible from a slightly later time to about twelve weeks. The heart (Latin cor) is a hollow, muscular organ that pumps blood through the blood vessels by repeated, rhythmic contractions. ... A left human ear. ...

Infection in the mother early in the third week may damage the heart. An infection in the eleventh week is less likely to damage the heart, but the baby may be born deaf. The word deaf, can have very different meanings based on the background of the person speaking or the context in which the word is used. ...

Reference

List of congenital disorders

Some other birth defects: Aicardi syndrome is a congenital disorder thought to result from an abnormality of the X chromosome and characterized by absence of the corpus callosum, retinal abnormalities, and seizures (often infantile spasms). ... Amelia is the birth defect of lacking one or more limbs. ... ... Cephalic disorders are congenital conditions that stem from damage to, or abnormal development of, the budding nervous system. ... Angelman syndrome (AS) is neurological disorder in which severe learning difficulties are associated with a characteristic facial appearance and behavior. ... Barth syndrome is a rare genetic disorder that affects at least fifty (~ 70) worldwide families. ... Beckwith-Wiedemann syndrome (BWS) is a very rare genetic overgrowth syndrome (prevalence of about 1 in 36,000). ... Bloom syndrome is a genetic condition characterized by prenatal growth delay and a butterfly rash in the mid-face region. ... A painting of Chang and Eng Bunker, circa 1836 Conjoined human fetuses Conjoined twins can occur in non-human animal species. ... 5p- karyotype Cri du chat syndrome, also called deletion 5p syndrome, or 5p minus, is a rare genetic disorder due to a missing portion of chromosome 5. ... The Ectodermal Dysplasias are describes as heritable conditions in which there are abnormalities of two or more ectodermal structures such as the hair, teeth, nails, sweat glands, cranial-facial structure, digits and other parts of the body. ... A thin upper lip and a smooth philtrum are signs of FAS Fetal alcohol spectrum disorder is an umbrella term used to describe fetal alcohol syndrome (FAS) and the less noticeable, but sometimes equally serious, fetal alcohol effects (FAE). ... Freeman-Sheldon Syndrome (also known as Whistling Face Syndrome) is a rare genetic condition which characteristically includes a small whistling mouth, a flat mask-like face, club feet, joint contractures usually involving the fingers and hands, and under-development of the cartilage of the nose. ... Gastroschisis is a type of abdominal wall defect in which the intestines and sometimes other organs develop outside the fetal abdomen through an opening in the abdominal wall. ... Cephalic disorders are congenital conditions that stem from damage to, or abnormal development of, the budding nervous system. ... Summary Jacobsen Syndrome, also known as 11q deletion, is a congenital disorder that occurs due to a partial deletion of the terminal band on chromosome 11. ... Lobster hand is a rare congenital deformity of the hand where the middle digit is missing, and the hand is cleft where the metacarpal of the finger should be. ... XXY karyotype Klinefelters syndrome is a condition caused by a chromosome abnormality in males (specifically, a nondisjunction); sufferers have a pair of X sex chromosomes instead of just one. ... Cephalic disorders are congenital conditions that stem from damage to, or abnormal development of, the budding nervous system. ... In medicine, the neurofibromatoses (singular, neurofibromatosis) are certain genetic disorders of the nervous system. ... Noonan Syndrome (NS) is a relatively common congenital genetic condition which affects both males and females. ... Prader-Willi syndrome is a genetic disorder in which seven genes (or some subset thereof) on chromosome 15 are missing or unexpressed (chromosome 15q partial deletion). ... Proteus Syndrome (PS) is a congenital disorder that causes skin overgrowth, atypical bone development, and tumour appearance over half the body. ... Introduction Rett syndrome (Retts syndrome, Rett disorder) is a progressive neurological disorder, one of the leading disorders of mental retardation in females. ... Rubinstein-Taybi syndrome (also known as Broad Thumb-Hallux syndrome) is a condition characterized by short stature, moderate to severe mental retardation, distinctive facial features, and broad thumbs and first toes. ... Cephalic disorders are congenital conditions that stem from damage to, or abnormal development of, the budding nervous system. ... Situs inversus causes the positions of the heart and lungs to be mirrored. ... Smith-Lemli-Opitz syndrome is a developmental disorder that affects many parts of the body. ... A triple-x female is a female posessing three X Chromosomes. ... Patau syndrome, also known as Trisomy 13, is a chromosomal aberration, a disease in which a patient has an additional chromosome 13. ... Usher syndrome is a genetic disease causing deaf-blindness. ... Waardenburg syndrome is a genetic disorder associated with hearing loss and changes in skin and hair pigmentation. ... Werner syndrome is a rare, autosomal-recessive disorder whose most recognizable characteristic is premature aging. ... 4p- karyotype Wolf-Hirschhorn syndrome, also known as deletion 4p and 4p- syndrome was first described in 1961 by U. Wolf and K. Hirschhorn and their co-workers. ...

Contents

Terminology

Risk of birth defects throughout gestation

Reference

List of congenital disorders

See also

Contents

Terminology GA_googleFillSlot("encyclopedia_square");

Risk of birth defects throughout gestation

Reference

List of congenital disorders

See also

Terminology