A large group of disorders arising during development that cause abnormality of the human body. Most are due to genetic factors such as inherited or spontaneous mutations, whereas others are caused by environmental influences during pregnancy such as exposure to harmful chemicals. The most severe and lethal disorders arise during the first 28 days of development and include gross brain anomalies and heart defects. The mildest malformations occur in the late stages of development and are often the result of dominant inheritance, whereas complex congenital syndromes are often the result of recessive inheritance. Seealso birth defect; Down syndrome.

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A congenital disorder is a disease or disorder that is present at birth. It may be the result of genetic abnormalities, the intrauterine (uterus) environment, errors of morphogenesis, or a chromosomal abnormality. The outcome of the disorder will further depend on complex interactions between the pre-natal deficit and the post-natal environment. Congenital disorders vary widely in causation and abnormalities. Any substance that causes birth defects is known as a teratogen.

Other terms and definitions

• A congenital physical anomaly is an abnormality of the structure of a body part. An anomaly may or may not be perceived as a problem condition. Many, if not most, people have one or more minor physical anomalies if examined carefully. Examples of minor anomalies can include curvature of the 5th finger (clinodactyly), a third nipple, 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 congenital physical anomaly that is deleterious, i.e. a structural defect perceived as a problem. A typical combination of malformations affecting more than one body part is referred to as a malformation syndrome.
• Birth defect is a widely-used term for a congenital malformation, i.e. a congenital, physical anomaly which is recognizable at birth, and which is significant enough to be considered a problem. According to the CDC most birth defects are believed to be caused by a complex mix of factors including genetics, environment, and behaviors. Though many birth defects have no known cause.
• Genetic disorder or diseases 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 congenital metabolic disease is also referred to as an inborn error of metabolism. Most of these are single gene defects, usually heritable. Many affect the structure of body parts but some simply affect the function.

See also

• Congenital abnormality
• List of congenital disorders
• ICD-10 Chapter Q: Congenital malformations, deformations and chromosomal abnormalities
• List of ICD-9 codes 740-759: Congenital anomalies
• Mitochondrial disease
• March of Dimes

References

• CDC’s National Center on Birth Defects and Developmental Disabilities
• The National Library of Medicine or MEDLINE/PubMed MeSH (medical subject heading) term
• Birth Defects Are Preventable
• James F. Crow, "The High Spontaneous Mutation Rate: Is it a Health Risk?"
• American College of Medical Genetics

External links

• CDC’s National Center on Birth Defects and Developmental Disabilities
• Comprehensive coverage of congenital disorders and birth defects at Answers.com