Congenital malformations - Edocr

112 PART III CRANIOFACIAL MALFORMATIONS
Figure 16-1. A preauricular tag indicated by
arrow. (Reprinted with permission from Jones
KL, ed. Smith’s Recognizable Patterns of Human
Malformation. 5th ed., p. 730. Copyright
1997, with permission from Elsevier.)
fusion of the hillocks by the end of the eighth
week of gestation produces the characteristic
shape of the auricle. The auricle and external
acoustic meatus appear to migrate up the side
of the developing face from their original cervical
location to reach their normal position by
the fourth month post conception, largely due
to lower facial and mandibular growth. 4
ASSOCIATED ANOMALIES AND
SYNDROMES
External ear anomalies occur as frequent findings
in over 100 genetic disorders and syndromes, multiple
chromosome abnormalities, and in infants
Figure 16-2. A preauricular pit indicated by
arrow. (Reprinted with permission from Jones
KL, ed. Smith’s Recognizable Patterns of Human
Malformation. 5th ed., p. 730. Copyright
1997, with permission from Elsevier.)
with diabetic embryopathy. 4 Some of the most
common disorders are listed in Table 16-1.
Noonan syndrome is one of the common multiple
congenital anomaly syndromes (incidence
of 1 in 1000–2500) associated with external ear
anomalies. Noonan syndrome is an autosomal
dominant disorder characterized by short stature,
congenital heart defect (frequently pulmonic
stenosis), broad or webbed neck, developmental
delay, and characteristic facies. Typical facial
features include hypertelorism, downslanting
palpebral fissures, and low-set, posteriorly rotated
ears with thickened helices. Approximately 50%
of affected individuals have a mutation in the
PTPN11 gene.