Stature or length, limb segments, and head circumference are proportionate in symmetrical or harmonic growth failure, and disproportionate in asymmetrical or dysharmonic dwarfism. Disproportion of the head, thorax, or limbs often suggests a skeletal dysplasia as will be discussed in Chapter 11. Proportionate growth failure of stature and limbs may be accompanied by a slightly larger head circumference in nutritional deficiencies (“head-sparing”) or by a slightly smaller head circumference in some congenital syndromes. Table 10.1 summarizes various syndromes with proportionate growth failure, classifying them by time of onset (prenatal and/or postnatal) and by accompanying changes in head circumference (with or without microcephaly).
Syndromes with symmetrical intrauterine growth retardation include many chromosomal and teratogenic syndromes discussed in Chapters 5–7. Intrauterine growth retardation is a harbinger for congenital disease, and a thorough investigation of maternal health, gestational history, and the fetal karyotype is often indicated. Once disorders such as fetal alcohol syndrome, Cri-du-Chat syndrome, and trisomy 13/18 are excluded by physical and laboratory findings, the clinician should begin considering syndromes with primary growth failure. Since isolated fetal disease (e.g., cardiac anomaly, renal anomaly) rarely produces intrauterine growth failure, a more global process must be suspected. Table 10.1 lists the more common syndromes with growth failure that do not involve obvious karyotypic changes. These disorders will exhibit proportionately small birth measurements and/or symmetrical failure to thrive. Any clinician concerned about shortened limbs, small thorax, frontal bossing with a shallow nasal bridge, or certain skeletal anomalies should obtain a skeletal radiographic survey to evaluate the possibility of a skeletal dysplasia (dwarfism – see Chapter 11).