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In the mid-1960s, David W. Smith coined the term dysmorphology to describe the field of medicine devoted to the study of abnormal human development.1 His intent was to propose a term that both replaced teratology (whose literal meaning and reference to monsters was pejorative) and captured the essence of the discipline. The purpose of this section is to summarize the principles of dysmorphology and, by doing so, provide an approach to the child with birth defects.2

Certain terms require definition in conceptualizing this approach: A syndrome is a pattern of birth defects that are etiologically related and regularly recur in different individuals (eg, Down syndrome). In other areas of medicine, the word syndrome is used less specifically and often refers to a specific set of symptoms that are not necessarily etiologically related (eg, nephrotic syndrome).

A sequence is a primary defect with a secondary cascade of structural changes. Birth defects that represent a sequence are usually localized to a single body area. Whereas a sequence can often be misinterpreted as a group of malformations, more critical inspection reveals a single malformation and a subsequent disruption or deformation. For example, the Pierre Robin sequence is caused by a primary abnormality in mandibular development that produces disruption of palatal closure and secondary obstruction of the airway by the tongue. A sequence can occur in isolation or be a component of an underlying syndrome diagnosis. For example, about 20% of children with Pierre Robin sequence have a disorder of connective tissue called Stickler syndrome (characterized by joint hyperextensibility, other skeletal manifestations and severe myopia).

An association is two or more primary defects that occur in the same individuals more often than is expected by chance. Defining a group of defects as an association suggests that the anomalies are etiologically related to one another, yet the nature and mechanism of that relationship remains unclear. For example, children with defects of the vertebrae, anus, trachea and esophagus, radius, and kidneys (renal) are often labeled with the acronym VATER association. Associations tend to be etiologically heterogenous more often than syndromes, and fewer characteristics of an association are observed in each affected child.

The approach to a child with birth defects is multifaceted and includes the collection of phenotypic data, determination of the immediate and long-term issues of care, and the provision of the family with psychological support (Fig. 178-1). The ability to recognize and interpret minor and major anomalies is an important skill that is required for evaluating a child with a birth defect2 and is important in the collection of clinical data.

Figure 178-1.

The approach to the management of the child with congenital anomalies. Note the diagnostic pathway and the psychosocial path are in parallel. The step involving the categorization of the problem may lead to one of the other diagnostic ...

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