Enlarged parietal foramina: findings on prenatal ultrasound and magnetic resonance imagingA 35-year-old G2P1L1 woman of European descent, whose pregnancy had been initially uncomplicated, underwent fetal ultrasound at 21 weeks of gestation. This examination showed large bilateral choroid plexus cysts extending into the anterior horns and two focal occipital protrusions. She was referred for suspicion of fetal encephalocele (Figure 1) and reported a significant family history of posterior calvarial defects ( Figure 2). She herself had two calvarial defects, each measuring 30 × 30 mm, at the posterior part of the parietal bones. Fetal magnetic resonance imaging (MRI) at 22 weeks of gestation demonstrated bilateral calvarial foramina measuring 18.9-19.6 mm with cerebrospinal fluid-filled protrusions not involving brain tissue. The remainder of the fetal anatomy was normal. A male infant was delivered at 39 weeks of gestation. The neonate had an anterior fontanelle measuring 35 × 35 mm and a posterior fontanelle measuring 5 × 5 mm. There were bilateral parietal foramina joined across the midline, located between the anterior fontanelle and the posterior fontanelle. There was also a separation of 2 mm along the lambdoid, sagittal and coronal sutures. The infant's growth and development were normal at 17-month follow-up.DNA analysis on the mother identified an R244W (c.730C > T) mutation in the ALX4 gene. The mutation was found to be located in helix II of the crucial DNAbinding homeodomain. This is a novel mutation and we believe it is the cause of the familial enlarged parietal foramina.Enlarged parietal foramina consist of symmetrical, paired openings in the parietal bones, located close to the intersection of the sagittal and lambdoid sutures. They are caused by insufficient ossification around the parietal notch, which is normally completed by 20 weeks of gestation 1 . The openings decrease in size with age, and significant intrafamilial heterogeneity has been reported. They are generally benign but have been reported to be associated with abnormal venous anatomy and seizures 2,3 . The key to the diagnosis of enlarged parietal foramina in our case was careful documentation of family history (five generations were affected) and examination of affected family members (the mother and her elder daughter). The bilaterality of the protrusions, as seen on the fetal ultrasound scan, also points to this diagnosis as encephalocele and meningocele are almost always in the midline, or in some exceptional circumstances, unilateral. A few prenatally detected cases of enlarged L E T T E R S T O T H E E D I T O R 522Letters to the Editor parietal foramina have been reported 4 -6 . In the case described by Salamanca et al. 6 , family history could be traced back three generations along the paternal side, indicating the importance of including the father in the evaluation. Recognition of this condition is important as it alleviates anxiety associated with 'suspected encephalocele' and allows minimization of head trauma at deliv...

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