Congenital microcephaly: phenotypic features in a consecutive sample of newborn infants.

OBJECTIVE: We compared the prevalence of major and minor anomalies in a consecutive sample of newborn infants with congenital microcephaly with that among normocephalic infants.

STUDY DESIGN: Head measurements from >19,000 liveborn infants at 1 hospital during the years 1991 and 1992 were reviewed. Infants whose head circumference was in the lowest quartile (n = 850) were remeasured by research assistants to identify all whose head circumference was 2 SD below the mean for gestational age; 106 infants with congenital microcephaly were identified. Infants with microcephaly (n = 65) and 294 infants in a control group were examined systematically for major malformations and minor physical features.

RESULTS: Four (6.2%) of the 65 infants examined either had a major malformation or were considered dysmorphic. One of the 4 had a specific multiple malformation syndrome, and 1 dysmorphic infant had a rare metabolic defect. Overall, the infants with microcephaly did not have a higher frequency of minor anomalies. However, there was a higher frequency of frontal bossing, small chin, and short nose with anteverted nares, which was associated with small body size rather than microcephaly.

CONCLUSIONS: Congenital microcephaly is infrequently accompanied by major malformations and occurs rarely as part of a recognizable syndrome.