Birth defects can be placed into one of the following established categories:• Deformation. Deformation anomalies have no inherent genetic basis. Rather

mechanical forces have altered the shape of the structure. Talipes equinovarus, or clubfoot, is the classic example of a deformation. Although the lower limbs were genetically programmed to form normally, external forces (such as a decreased amount of amniotic fluid) or internal forces (such as neurological impairment) prevented such development.

• Disruption. Like deformation, the genetic program of the structure in disruption was normal. However, the normal developmental process was interrupted by some mechanism, causing the anomaly. Examples of disruption are the anomalies observed in newborns exposed to cocaine in utero. This drug a known vasoconstrictive agent. Is believed to cause malformations ranging from intestinal atresias to craniofacial structures by temporary restricting blood supply to the developing structures.

• Dysplasia. Dysplasia refers to a general abnormality at the level of cellular organization in a specific tissue. One example would be a connective tissue disorder, such as Marfan’s syndrome

• Malformation. A malformation is an anomaly in which the developmental process was abnormal from the outset. An example is a cleft lip and palate. In which the structures that joint the lip and palate do not fuse normally. In general malformations are caused by a genetic mutation, congenital infection, teratogen exposure.

• Syndrome. A child will often have multiple malformations and it is important to determine their relationship. In a syndrome the observed malformations are pathogenetically related to a single cause. For example in Marfan’s syndrome, the tall stature, dilated aortic roor, loose joints, and lens dislocations are all caused by an abnormality in fibrillin.

• Association. An association is the nonrandom occurrence of a set of malformations that are not pathogenetically related. VATER or VACTERL – vertebrae, imperforate anus, cardiac anomalies, TEF, renal anomalies, limb anomalies (radial defect). Although these anomalies occur more frequently together than they do separately, they are not believed to be casually related. That is, they are not caused by the same genetic or teratogenic origin.

• Field defect. A field defect is a set of malformations that are grouped in a located area of a body or a so-called developmental field. Abnormal developmental stimuli, such those caused by a teratogen or a mutated gene result in a developmental field defect. One example is a cloacal extrophy.

• Sequence. Sequence is a series of findings that are derived from a single anomaly or mechanical force. One example is Pier Robin sequence – the constellation of a small jaw, a midline U-shaped cleft palate and relatively large and protruding tongue. The primary anomaly is the small jaw, which fails to provide an adequate room for the tongue and displaces it in a superior direction. The tongue then prevents closure of the palatine shelves, causing the cleft palate. It is important to mention that the borders of these definitions are not firm, and overlap does occur. F.e. P-R syndrome can be an isolated findings or a feature of several genetic syndromes.