Results from Genetic Studies in Patients Affected with Craniosynostosis: Clinical and Molecular Aspects

Chromatinopathies: insight in clinical aspects and underlying epigenetic changes

Chromatinopathies (CPs), a group of rare inborn defects characterized by chromatin state imbalance, have evolved from initially resembling Cornelia de Lange syndrome to encompass a wide array of genetic diseases with diverse clinical presentations. The CPs classification now includes human developmental disorders caused by germline mutations in epigenes, genes that regulate the epigenome. Recent advances in next-generation sequencing have enabled the association of 154 epigenes with CPs, revealing distinctive DNA methylation patterns known as episignatures.It has been shown that episignatures are unique for a particular CP or share similarities among specific CP subgroup. Consequently, these episignatures have emerged as promising biomarkers for diagnosing and treating CPs, differentiating subtypes, evaluating variants of unknown significance, and facilitating targeted therapies tailored to the underlying epigenetic dysregulation.The following review was conducted to collect, summarize, and analyze data regarding CPs in such aspects as clinical evaluation encompassing long-term patient care, underlying epigenetic changes, and innovative molecular and bioinformatic methodologies that have been devised for the assessment of CPs. We have also shed light on promising novel treatment options that have surfaced in recent research and presented a synthesis of ongoing clinical trials, contributing to the current understanding of the dynamic and evolving nature of CPs investigation.

The value of genome-wide analysis in craniosynostosis

Background: This study assessed the diagnostic yield of high-throughput sequencing methods in a cohort of craniosynostosis (CS) patients not presenting causal variants identified through previous targeted analysis. Methods: Whole-genome or whole-exome sequencing (WGS/WES) was performed in a cohort of 59 patients (from 57 families) assessed by retrospective phenotyping as having syndromic or nonsyndromic CS. Results: A syndromic form was identified in 51% of the unrelated cases. A genetic cause was identified in 38% of syndromic cases, with novel variants detected in FGFR2 (a rare Alu insertion), TWIST1, TCF12, KIAA0586, HDAC9, FOXP1, and NSD2. Additionally, we report two patients with rare recurrent variants in KAT6A and YY1 as well as two patients with structural genomic aberrations: one with a 22q13 duplication and one with a complex rearrangement involving chromosome 2 (2p25 duplication including SOX11 and deletion of 2q22). Moreover, we identified potentially relevant variants in 87% of the remaining families with no previously detected causal variants, including novel variants in ADAMTSL4, ASH1L, ATRX, C2CD3, CHD5, ERF, H4C5, IFT122, IFT140, KDM6B, KMT2D, LTBP1, MAP3K7, NOTCH2, NSD1, SOS1, SPRY1, POLR2A, PRRX1, RECQL4, TAB2, TAOK1, TET3, TGFBR1, TCF20, and ZBTB20. Conclusion: These results confirm WGS/WES as a powerful diagnostic tool capable of either targeted in silico or broad genomic analysis depending on phenotypic presentation (e.g., classical or unusual forms of syndromic CS).

Ophthalmic Manifestations of Unilateral Coronal Synostosis

PURPOSE

To summarize the ophthalmic manifestations of unilateral coronal synostosis patients.

METHODS

We performed a literature search in the electronic database of PubMed, CENTRAL, Cochrane, and Ovid Medline guided by Preferred Reporting Items for Systematic Reviews and Meta-Analysis Statement for studies evaluating ophthalmic manifestations of unilateral coronal synostosis.

RESULTS

Unilateral coronal synostosis, also called unicoronal synostosis, may be mistaken for deformational plagiocephaly, an asymmetric skull flattening common in newborns. Characteristic facial features, however, distinguish the two. Ophthalmic manifestations of unilateral coronal synostosis include a "harlequin deformity", anisometropic astigmatism, strabismus, amblyopia, and significant orbital asymmetry. The astigmatism is greater on the side opposite the fused coronal suture. Optic neuropathy is uncommon unless unilateral coronal synostosis accompanies more complex multi-suture craniosynostosis. In many cases, surgical intervention is recommended; without intervention, skull asymmetry and ophthalmic disorders tend to worsen with time. Unilateral coronal synostosis can be managed by early endoscopic stripping of the fused suture and helmeting through a year of age or by fronto-orbital-advancement at approximately 1 year of age. Several studies have demonstrated that anisometropic astigmatism, amblyopia, and severity of strabismus are significantly lower after earlier intervention with endoscopic strip craniectomy and helmeting compared to treatment by fronto-orbital-advancement. It remains unknown whether the earlier timing or the nature of the procedure is responsible for the improved outcomes. As endoscopic strip craniectomy can only be performed in the first few months of life, early recognition of the facial, orbital, eyelid, and ophthalmic characteristics by consultant ophthalmologists enables expeditious referral and optimized ophthalmic outcomes.

CONCLUSION

Timely identification of craniofacial and ophthalmic manifestations of infants with unilateral coronal synostosis is important. Early recognition and prompt endoscopic treatment appears to optimize ocular outcomes.