List of birth defect terminology starting with A.
Agenesis – Absence of part(s) of the body.
Agenesis, aplasia, or hypoplasia of the lung – The absence or incomplete development of a lung or lung tissue.
Anencephaly – Congenital absence of the skull, with cerebral hemispheres completely missing or reduced to small masses attached to the base of the skull. Anencephaly is not compatible with life.
Aniridia – The complete absence of the iris of the eye or a defect of the iris. Can be congenital or traumatically induced.
Anopthalmia – A developmental defect characterized by complete absence of the eyes, or by the presence of vestigial eyes.
Anotia – A congenital absence of one or both ears.
Aortic valve stenosis – A cardiac anomaly characterized by a narrowing or stricture of the aortic valve. This condition causes abnormal cardiac circulation and pressure in the heart during contractions. This condition can be repaired surgically in some cases.
Atresia Imperforation – Absence or closure of a normal opening.
Atrial Septal Defect – A congenital cardiac malformation in which there are one or several openings in the atrial septum (muscular and fibrous wall between the right and left atria) allowing a mixing of oxygenated and unoxygenated blood. The openings vary in size and may resolve without treatment or may require surgical treatment. Also called ostium secundum defect.