The Influence of Epigenetic Factors in Four Pairs of Twins With Non-Syndromic Craniosynostosis:

Craniosynostosis in Isfahan, Iran: A Cross-Sectional Study

Background

Craniosynostosis is the premature closure of cranial sutures. According to the literature, several factors are related to this disorder. Due to the relatively high prevalence in Iran and a lack of related studies in this region, this study was designed to determine the characteristics of a group of these patients in this region.

Methods

This cross-sectional study was performed from 2016 to 2019 at two tertiary referral hospitals for children in Isfahan, Iran. Studied variables included: age, sex, birth weight, type of craniosynostosis, concurrent anomalies, parents' age, father's job, fetus position, maternal parity, history of maternal smoking during the pregnancy, use of fertility assistant treatments, and history of maternal endocrine disorders.

Results

We had 125 infants, including 82 (65.6%) males and 43 (34.4%) females. The most common type was metopic (29%). The most common concurrent disorder was congenital heart defects (43.2% of patients). The mean age of infants was 0.62SD0.59 years. Gender distribution showed a significant difference (p value = 0.006). While the metopic (n = 31) type was significantly more common in boys, the coronal type was female predominant (n = 14). The mean age of fathers was 33.08SD5.66 and mothers, was 29.02SD5.70 with no significant difference (p value = 0.669 and 0.149, respectively). Other evaluated factors also didn't show a significant difference.

Conclusion

Craniosynostosis is more prevalent in boys, especially the metopic type. Coronal type has a female predilection. The most common subtype is metopic. The most common concurrent congenital disorder is congenital heart defects.

A novel pathogenic variant of DNMT3A associated with craniosynostosis: a case report of Heyn-Sproul-Jackson syndrome

Pathogenic variants of DNMT3A have been implicated in Tatton-Brown-Rahman syndrome, an overgrowth disorder with macrocephaly and intellectual disability. However, there are recent reports of variants in the same gene giving rise to an opposing clinical phenotype presenting with microcephaly, growth failure, and impaired development-named Heyn-Sproul-Jackson syndrome (HESJAS). Here, we present a case of HESJAS caused by a novel pathogenic variant of DNMT3A. A five-year-old girl presented with severe developmental delay. Perinatal and family history were non-contributory. Physical exam showed microcephaly and facial dysmorphic features, and neurodevelopmental assessments revealed profound global developmental delay. Brain magnetic resonance imaging findings were normal; however, brain 3D computed tomography revealed craniosynostosis. Next generation sequencing revealed a novel heterozygous variant in DNMT3A (NM_175629.2: c.1012_1014 + 3del). The patient's parents did not carry the variant. In this report, a novel feature associated with HESJAS (craniosynostosis) is described, along with a more detailed account of clinical manifestations than those in the original report.

Ciliary Signalling and Mechanotransduction in the Pathophysiology of Craniosynostosis

Craniosynostosis (CS) is the second most prevalent inborn craniofacial malformation; it results from the premature fusion of cranial sutures and leads to dimorphisms of variable severity. CS is clinically heterogeneous, as it can be either a sporadic isolated defect, more frequently, or part of a syndromic phenotype with mendelian inheritance. The genetic basis of CS is also extremely heterogeneous, with nearly a hundred genes associated so far, mostly mutated in syndromic forms. Several genes can be categorised within partially overlapping pathways, including those causing defects of the primary cilium. The primary cilium is a cellular antenna serving as a signalling hub implicated in mechanotransduction, housing key molecular signals expressed on the ciliary membrane and in the cilioplasm. This mechanical property mediated by the primary cilium may also represent a cue to understand the pathophysiology of non-syndromic CS. In this review, we aimed to highlight the implication of the primary cilium components and active signalling in CS pathophysiology, dissecting their biological functions in craniofacial development and in suture biomechanics. Through an in-depth revision of the literature and computational annotation of disease-associated genes we categorised 18 ciliary genes involved in CS aetiology. Interestingly, a prevalent implication of midline sutures is observed in CS ciliopathies, possibly explained by the specific neural crest origin of the frontal bone.

Familial Pfeiffer Syndrome: Variable Manifestations and Role of Multidisciplinary Team Care

Pfeiffer syndrome is one of the autosomal dominant craniofacial syndromes. Classical clinical manifestations are coronal suture synostosis causing brachycephaly, midface retrusion, airway compromise, broad thumbs, and toes. Pfeiffer syndrome type I (classic type) is associated with FGFR1 mutation. However, wide range of clinical manifestations, with and without craniosynostosis, have been reported. Here, we present a family of Pfeiffer syndrome across 3 generations with identical FGFR1: c.755C>G (p.Pro252Arg) mutation. Where the members of the youngest generation have no cranial involvement. Lastly, we propose a guideline management for familial Pfeiffer syndrome management.

Single-suture craniosynostosis and the epigenome: current evidence and a review of epigenetic principles

Craniosynostosis (CS) is a congenital disease that arises due to premature ossification of single or multiple sutures, which results in skull deformities. The surgical management of single-suture CS continues to evolve and is driven by a robust body of clinical research; however, the molecular underpinnings of CS remain poorly understood. Despite long-standing hypotheses regarding the interaction of genetic predisposition and environmental factors, formal investigation of the epigenetic underpinnings of CS has been limited. In an effort to catalyze further investigation into the epigenetic basis of CS, the authors review the fundamentals of epigenetics, discuss recent studies that shed light on this emerging field, and offer hypotheses regarding the role of epigenetic mechanisms in the development of single-suture CS.