Congenital malformations - Edocr

CHAPTER 1 DYSMORPHOLOGY 7
TABLE 1-2 Common Teratogens and Associated Anomalies
Vulnerable Period
Associated Congenital Anomalies
Teratogen Drugs
Antihypertensive 13th week-term Hypocalvaria, renal failure, pulmonary
ACE inhibitors
hypoplasia, death
Anticonvulsants
Phenytoin 18–60 days Cleft lip/palate, congenital heart defect,
hypoplasia of nails
Valproic acid 18–60 days Hypertelorism, hyperconvex nails, septooptic
dysplasia, cleft lip/palate, limb
defects, microcephaly
Retinoids 18–60 days CNS/ear defects, cleft lip/palate, heart
defects, eye anomalies
Anticoagulants
Warfarin 6–9 weeks Nasal hypoplasia, eye anomalies,
hypoplastic phalanges
Androgens 2–24 weeks Genital tract abnormalities
Infections
Rubella First trimester Cataract, microcephaly, microopthalmia,
heart defects
Varicella zoster 8–20 weeks Microcephaly, limb hypoplasia, cutaneous
scars
Maternal Disorders
Diabetes First trimester Neural tube defects, cardiac defects,
caudal regression syndrome
Phenylketonuria Mainly first trimester IUGR, microcephaly, dysmorphic features,
maxillary and mandibular hypoplasia,
cardiac defects, cleft lip/palate
Miscellaneous
Alcohol First trimester Microcephaly, maxillary hypoplasia,
heart defects
CNS, central nervous system; IUGR, intrauterine growth retardation; ACE, angiotensin-converting enzyme.
and the genetic susceptibility of the embryo. It
is likely that the interactions between genes and
environmental factors are responsible for most
birth defects related to teratogenic exposures.
Classification of Congenital
Anomalies
Although all congenital malformations are a result
of an aberrant structural development, the underlying
cause/mechanism, extent of maldevelopment,
consequences, and the risks of recurrence
are variable. Congenital anomalies can be classified
either based on timing of insult, underlying
histological changes, or based on its medical
and social consequences.
A. Classification based on timing of insult.
Congenital anomalies can be placed into the
following three categories on the basis of
developmental stage during which the aberration
in development took place.
1. Malformation. A malformation is a morphologic
defect of an organ, part of an
organ, or a region of the body due to