defect is a topic covered in the Taber's Medical Dictionary.

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(dē′fekt″ )

(di-fekt′ )
[L. defectus, weakness, failure]
A flaw or imperfection.
defective (di-fek′tiv ), adj.
Common Birth Defects

Type of DefectExamplesApproximate Prevalence per 10,000 BirthsComments
ChromosomalDown syndrome (trisomy 21)13Increases with maternal age over 35 years
Trisomy 182.3
InfectiousVaricella-zoster infection (chickenpox)7
MetabolicPhenylketonuria (PKU)3.5
StructuralCleft lip and/or palate10
Neural tube defects, including anencephaly and spina bifida3Folate supplementation during pregnancy prevents neural tube defects
Transposition of the great vessels5
ToxicFetal alcohol spectrum disorders2-15Varies with prevalence of alcohol use in the community; preventable with abstinence
Isotretinoin (acne medication)Avoid all pregnancies during therapy with isotretinoin

Birth Defects by Categories, with Examples
Structural/Anatomical DefectsExamples
CraniofacialCleft lip or cleft palate; craniosynostosis
Heart and blood vesselsAortic coarctation; hypoplastic left heart; patent ductus arteriosus; tetralogy of Fallot; transposition of the great vessels; ventricular septal defect
LimbsAbsent limbs or digits; conjoined limbs or digits; extra limbs or digits; malformations, e.g., club foot
Neural tubeMyelomeningocele; spina bifida; encephalocele
Chromosomal/genetic syndromes or microdeletionsExtra chromosomes, e.g., Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), Klinefelter syndrome; sickle cell anemia
Digestive/Intestinalgastroschisis; Hirschprung disease; pyloric stenosis
ExcretoryCongenital hydronephrosis; renal agenesis or dysplasia; hypospadias; choanal atresia
Functional/Developmental DefectsExamples
Neurological/Psychiatric/BehavioralCongenital hypothyroidism; fetal alcohol syndrome
MetabolicInborn errors of metabolism, e.g., homocystinuria, phenylketonuria
DegenerativeLysosomal storage diseases; muscular dystrophies
Birth defects affecting special sense organsFor example, congenital deafness; congenital cataract

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