Congenital microcephaly detected by prenatal ultrasound: genetic aspects and clinical significance

Objective The aim of this study was to analyze fetuses with prenatally diag nosed microcephaly including the nature of associated anomalies and the gen etic-diagnostic implications. Design Retrospective study design. Methods A total of 30 fetuses with reliable dates and with prenatally diagn osed microcephaly as a common feature were analyzed. Results Microcephaly was diagnosed at a mean gestational age of 28 weeks. M ore than half of the fetuses were also small for gestational age. Five subs ets of microcephaly emerged from this study: (1) isolated microcephaly (16. 7%); (2) microcephaly due to holoprosencephaly (16.7%); (3) microcephaly as sociated with chromosomal disorders (23.3%); (4) microcephaly as part of a genetic syndrome (20.0%): and (5) microcephaly as part of multiple anomalie s (23.3%). Conclusions In 25 out of 30 infants microcephaly proved to be part of a com plex problem, emphasizing the need of a inetrclrlotls search for structural anomalies and fetal karyotyping when biometric data are not according to g estational age. The etiologic heterogeneity and variability of microcephaly in genetic syndromes are among the more difficult issues in prenatal ultra sound in pregnancies either with an incidental finding of this anomaly or i n cases with a recurrence risk. The complex situations described in this st udy demonstrate the importance of follow up, post-mortem investigation and careful genetic counseling.