Phenotypic variability of syndromic craniosynostosis caused by c.833G > T in FGFR2: Clinical and genetic evaluation of eight patients from a five-generation family

A 3-Dimensional Morphometric Analysis of 4 Midsagittal Planes for CT Scan Reference Determination in Children with Syndromic Craniosynostosis

OBJECTIVE

To identify the suitable and practical midsagittal plane (MSP) reference for computed tomography (CT) scan skull analysis in patients with syndromic craniosynostosis.

DESIGN

Retrospective study.

SETTING

Tertiary referral hospital.

PATIENTS AND PARTICIPANTS

A total of 19 full skull CT scans of syndromic craniosynostosis patients.

METHODS

Seven craniofacial landmarks located on the midline and 4 MSPs that was previously published and clinically recognized (Planes: SPBaS, SPNSANS, SPLOrPo and SPZFTP) were constructed from the CT images. The absolute distance of every plane from 7 landmarks were then calculated. These distances were subsequently subjected to statistical analysis.

MAIN OUTCOME MEASURE(S)

The absolute distance of different MSPs from 7 landmarks.

RESULTS

The distances of landmarks measured to SPBaS were the highest, with the most prominent fluctuation. The fluctuation of the SPNSANS, SPLOrPo and SPZFTP had similar direction changes, with the latter being the closest. Pairwise comparisons demonstrated statistical differences (P < .008 using the Bonferroni correction) between the measured distances of A point (M = 0.25, SD = 0.16) and B point (M = 2.21, SD = 1.6) to SPNSANS. There were statistical significances between distances of B point (M = 1.68, SD = 1.07) and CG point (M = 0.55, SD = 0.37) to SPZFTP plane. There was no statistical significance on each landmark to SPLOrPo.

CONCLUSIONS

The study demonstrates that SPBaS is not recommended for MSP reference. While SPNSANS should be carefully selected, the application of SPLOrPo and SPZFTP are interchangeable, with the SPZFTP plane slightly exaggerating the mandible deviation relative to the superior and posterior of the midface.

Phenotypic variability of syndromic craniosynostosis caused by c.833G > T in FGFR2: Clinical and genetic evaluation of eight patients from a five-generation family

Objective

Craniosynostosis is the result of the early fusion of cranial sutures. Syndromic craniosynostosis includes but not limited by Crouzon syndrome and Pfeiffer syndrome. Considerable phenotypic overlap exists among these syndromes and mutations in FGFR2 may cause different syndromes. This study aims to investigate the explanation of the phenotypic variability via clinical and genetic evaluation for eight patients in a large pedigree.

Methods

For each patient, comprehensive physical examination, cranial plain CT scan with three‐dimensional CT reconstruction (3D‐CT), and eye examinations were conducted. Whole exome sequencing was applied for genetic diagnosis of the proband. Variants were analyzed and interpreted following the ACMG/AMP guidelines. Sanger sequencing was performed to reveal genotypes of all the family members.

Results

A pathogenic variant in the FGFR2 gene, c.833G > T (p.C278F), was identified and proved to be co‐segregate with the disease. Some symptoms of head, hearing, vision, mouth, teeth expressed differently by affected individuals. Nonetheless, all the eight patients manifested core symptoms of Crouzon syndrome without abnormality in the limbs, which could exclude diagnosis of Pfeiffer syndrome.

Conclusion

We have established clinical and genetic diagnosis of Crouzon syndrome for eight patients in a five‐generation Chinese family. Variability of clinical features among these familial patients was slighter than that in previously reported sporadic cases.