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.
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 ...