Numerous genetic conditions are evident and diagnosable during the neonatal period because of a specific pattern of clinical features often present on infant physical examination. This chapter reviews several of the more frequently observed genetic dysmorphic conditions neonatal practitioners are most likely to encounter in a newborn (apart from the common trisomies that are addressed separately in this textbook), which include: Turner syndrome (TS), 22q11.2 deletion syndrome, CHARGE (coloboma, heart defect, atresia choanae [also known as choanal atresia], retarded growth and development, genital abnormality, and ear abnormality) syndrome, and VACTERL (vertebral, anal, cardiac, tracheoesophageal, renal, and limb) association.
As several genetic syndromes and 1 association are discussed in this chapter, it is reasonable to define both entities. The term syndrome derives from the Greek and means “concurrence” or “along with, together.” Thus, a genetic syndrome refers to a pattern of congenital anomalies that can be explained by a common genetic or developmental cause. Syndromes often include developmental abnormalities and increased risk of recurrence in families. An association is a collection of physical findings and is considered a nonrandom occurrence; it is known not be a polytypic defect, sequence, or syndrome.1 Associations are generally not associated with an increased risk of recurrence.1
Identification of a specific genetic diagnosis during the immediate newborn period is helpful for appropriate medical management, as well as to provide the infant’s family with prognostic information and accurate recurrence risk information.
CLINICAL GENETICS EVALUATION
Physical examination of the neonate is essential in providing diagnostic accuracy as well as focusing differential diagnoses. The genetic dysmorphology evaluation is a careful physical examination of the infant in a head-to-toe manner, taking note of any facial or body asymmetries, malformations, or deformations that may be present externally. This also involves measuring and plotting the growth parameters (length, weight, and head circumference) on appropriate curves for gestational age, such that entities of microcephaly or microsomia are not neglected.
The neonatal head is evaluated by assessing the head shape, size of the anterior and posterior fontanelles, and cranial sutures. Close attention is paid to possible sutural ridging or unusual head shape that is distinct from transient postnatal vertex molding. Careful evaluation of the scalp is performed to uncover lesions such as cutis aplasia congenita or unusual hair patterning that may indicate an underlying cerebral malformation. Facial asymmetry or cranial nerve palsy is best visualized while the infant is crying. Presence of facial asymmetry is often seen in association with syndromes such as CHARGE or 22q11.2 deletion syndrome and thus is of significant diagnostic value.
Evaluation of the eyes with an ophthalmoscope is warranted such that red reflexes can be visualized and irides can be closely examined for the presence of colobomas, which tend to be located inferonasally. Certain ophthalmic anomalies, such as iris Brushfield spots (observed in Down syndrome), retinal coloboma, optic nerve hypoplasia, ...