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A male infant was delivered vaginally at 37+4 weeks after an uncomplicated pregnancy with normal antenatal ultrasonography. An abnormal head shape was noted, with normal head circumference, reduced biparietal diameter, orbital hypertelorism, short philtrum and microretrognathia (figure 1A–C). The skull felt soft when palpated. The rest of physical examination was normal. An X-ray (figure 1D), MRI and three-dimensional CT scan reconstruction of the skull (figure 1E,F) showed a severe defect in ossification of the calvaria and widely enlarged sutures. A skeletal survey showed no other abnormalities. Trio whole-exome sequencing identified p.Ser124ter (c.371C>A) heterozygous variant in RUNX2 gene in the proband. Cleidocranial dysplasia (CCD) was diagnosed. The baby was conservatively managed; he is now 10 months old, and an initial regrowth of skull bones has been detected on X-ray.
(A–C) Abnormal head shape with reduced biparietal diameter, orbital hypertelorism, short philtrum and microretrognathia. (D) Skull X-ray (lateral view) at 10 days of life reveals large ossification defects with hypoplastic parietal, frontal and temporal bones and large sutures. (E,F) Head CT scan with three-dimensional volume rendering reconstruction of the skull at 11 days of life clearly shows severe deficiency of all the cranial flat bones and wide diastasis of the cranial sutures.
CCD is a rare genetic skeletal dysplasia (prevalence 1/1.000.000), caused by mutations in the RUNX2 gene (6p21), following an autosomal dominant pattern of inheritance or resulting from a de novo mutation.1 2 More than 60 types of mutations have been identified, with no clear phenotype–genotype correlation.3 4 Typical presentation is characterised by the triad: delayed closure of the cranial sutures, hypoplastic/aplastic clavicles and dental abnormalities.1 2 Isolated severe calvarial phenotype is a very rare presentation instead.4 5 Long-term prognosis is generally good.1 Cranioplasty and bone grafting can be performed at an older age, while some cases show spontaneous partial regrowth.5 In case of suspicious findings on prenatal ultrasound, an elective caesarean section is recommended to prevent brain injury.5
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Footnotes
Contributors EB collected the patient data, performed a detailed literature search, drafted the initial manuscript and edited the manuscript according to feedback of the other authors. SA, EC and AP participated in the diagnosis of the patient and were involved in the management of clinical case. LP examined and interpreted MRIs. MM, CC and FMR contributed to the analysis and interpretation of data, and reviewed the manuscript. All authors have been involved in the patient’s care, approved the final manuscript as submitted and agree to be accountable for all aspects of the work.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; internally peer reviewed.