Growth and Clinical Characteristics of Children with Floating-Harbor Syndrome: Analysis of Current Original Data and a Review of the Literature

Floating-Harbor syndrome and provision of dental treatment: A case report of the dental considerations

Floating-Harbor syndrome (FHS) is a rare genetic syndrome with limited cases reported in the medical literature. It is an autosomal dominant condition with affected individuals carrying a pathogenic variant of the SRCAP gene. FHS cases show individuals having consistent facial features and differing levels of intellectual disability, which can affect their ability to receive different anaesthetic modalities and have capacity to consent for dental treatment. This case report focuses on the clinical management of a young adult with FHS requiring dental care with different treatment modifications tailored to the patient's individual needs. Further research and awareness of this syndrome is required to fully understand its consistent oral findings and varying intellectual abilities, to ensure appropriate and timely treatment provision. MeSH: dentistry, Floating-Harbor syndrome (FHS), SRCAP gene, clinical management.

Intrauterine growth in chromatinopathies: A long road for better understanding and for improving clinical management

BACKGROUND

Chromatinopathies are a heterogeneous group of genetic disorders caused by pathogenic variants in genes coding for chromatin state balance proteins. Remarkably, many of these syndromes present unbalanced postnatal growth, both under- and over-, although little has been described in the literature. Fetal growth measurements are common practice in pregnancy management and values within normal ranges indicate proper intrauterine growth progression; on the contrary, abnormalities in intrauterine fetal growth open the discussion of possible pathogenesis affecting growth even in the postnatal period.

METHODS

Among the numerous chromatinopathies, we have selected six of the most documented in the literature offering evidence about two fetal overgrowth (Sotos and Weaver syndrome) and four fetal undergrowth syndromes (Bohring Opitz, Cornelia de Lange, Floating-Harbor, and Meier Gorlin syndrome), describing their molecular characteristics, maternal biochemical results and early pregnancy findings, prenatal ultrasound findings, and postnatal characteristics.

RESULTS/CONCLUSION

To date, the scarce data in the literature on prenatal findings are few and inconclusive, even though these parameters may contribute to a more rapid and accurate diagnosis, calling for a better and more detailed description of pregnancy findings.

Floating-Harbor Syndrome: A Systematic Literature Review and Case Report

Floating-Harbor syndrome (FHS) is an extremely rare genetic disorder connected with a distinctive facial appearance, various skeletal malformations, delayed bone age, and expressive language delays. It is caused by heterozygous mutations in the Snf2-related CREBBP activator protein (SRCAP) gene. The aim of this paper is to describe the case of a 14-year-old male with FHS, referring to a review of the literature, and to collect all reported symptoms. In addition, the orthodontic treatment of the patient is described. For this, the electronic databases PubMed and Scopus were searched using the keyword "Floating-Harbor syndrome". Similar to previous cases in the literature, the patient presented with short stature; a triangular face with a large bulbous nose; deep-set eyes and narrow eyelid gaps; a wide mouth with a thin vermilion border of the upper lip; and dorsally rotated, small ears. They also presented some less-described symptoms, such as macrodontia and micrognathia. Moreover, mild mental retardation, microcephaly, and delayed psychomotor development were found. On the basis of an extraoral, intraoral examination, X-rays, and CBCT, he was diagnosed with overbite, canine class I and angle class III, on both sides. To the best of our knowledge, orthodontic treatment of this disease has not been assessed in detail so far, so this is the first case.

A Case of Floating-Harbor Syndrome with "Growth and Language Development Delay" as Its Clinical Manifestation

Background

Floating-Harbor syndrome (FHS) is a rare autosomal dominant inherited disease characterized primarily by short stature, delayed language development, and typical facial features. There are currently few case reports, diagnoses and treatments for these syndromes at home and abroad.

Case Description

This study reports a case of a boy with "growth and language development delay" as the predominant clinical manifestation. FHS was clinically diagnosed based on his growth hormone (GH) deficiency, significant bone age delay, left testicular hydrocele, and the whole exon gene in peripheral blood, which indicated heterozygous mutation of SRCAP gene. Following the treatment with recombinant human GH (rhGH), the child exhibited height increase benefits, and his articulation improved after language therapy.

Conclusion

Genetic testing facilitates early detection, diagnosis, and treatment of the FHS. Additionally, treatment with rhGH effectively increases the height of these children, and language rehabilitation is especially important for their language development.

Molecular Genetics and Pathogenesis of the Floating Harbor Syndrome: Case Report of Long-Term Growth Hormone Treatment and a Literature Review

Introduction: Floating Harbor syndrome (FHS) is an extremely rare disorder, with slightly more than a hundred cases reported worldwide. FHS is caused by heterozygous mutations in the SRCAP gene; however, little is known about the pathogenesis of FHS or the effectiveness of its treatment.

Methods: Whole-exome sequencing (WES) was performed for the definitive molecular diagnosis of the disease. Identified variants were validated using Sanger sequencing. In addition, systematic literature and public data on genetic variation in SRCAP and the effects of growth hormone (GH) treatment was conducted.

Results: We herein report the first case of FHS in the Russian Federation. The male proband presented with most of the typical phenotypic features of FHS, including short stature, skeletal and facial features, delayed growth and bone age, high pitched voice, and intellectual impairment. The proband also had partial growth hormone deficiency. We report the history of treatment of the proband with GH, which resulted in modest improvement in growth prior to puberty. WES revealed a pathogenic c.7466C>G (p.Ser2489*) mutation in the last exon of the FHS-linked SRCAP gene. A systematic literature review and analysis of available genetic variation datasets highlighted an unusual distribution of pathogenic variants in SRCAP and confirmed the lack of pathogenicity for variants outside of exons 33 and 34. Finally, we suggested a new model of FHS pathogenesis which provides possible basis for the dominant negative nature of FHS-causing mutations and explains limited effects of GH treatment in FHS.

Conclusion: Our findings expand the number of reported FHS cases and provide new insights into disease genetics and the efficiency of GH therapy for FHS patients.

Chromatin remodelling complexes in cerebral cortex development and neurodevelopmental disorders

The diverse number of neurons in the cerebral cortex are generated during development by neural stem cells lining the ventricle, and they continue maturing postnatally. Dynamic chromatin regulation in these neural stem cells is a fundamental determinant of the emerging property of the functional neural network, and the chromatin remodellers are critical determinants of this process. Chromatin remodellers participate in several steps of this process from proliferation, differentiation, migration leading to complex network formation which forms the basis of higher-order functions of cognition and behaviour. Here we review the role of these ATP-dependent chromatin remodellers in cortical development in health and disease and highlight several key mouse mutants of the subunits of the complexes which have revealed how the remodelling mechanisms control the cortical stem cell chromatin landscape for expression of stage-specific transcripts. Consistent with their role in cortical development, several putative risk variants in the subunits of the remodelling complexes have been identified as the underlying causes of several neurodevelopmental disorders. A basic understanding of the detailed molecular mechanism of their action is key to understating how mutations in the same networks lead to disease pathologies and perhaps pave the way for therapeutic development for these complex multifactorial disorders.

Whole-genome analysis as a diagnostic tool for patients referred for diagnosis of Silver-Russell syndrome: a real-world study

BACKGROUND

Silver-Russell syndrome (SRS) is an imprinting disorder characterised by prenatal and postnatal growth restriction, but its clinical features are non-specific and its differential diagnosis is broad. Known molecular causes of SRS include imprinting disturbance, single nucleotide variant (SNV), CNV or UPD affecting several genes; however, up to 40% of individuals with a clinical diagnosis of SRS currently receive no positive molecular diagnosis.

METHODS

To determine whether whole-genome sequencing (WGS) could uncover pathogenic variants missed by current molecular testing, we analysed data of 72 participants recruited to the 100,000 Genomes Project within the clinical category of SRS.

RESULTS

In 20 participants (27% of the cohort) we identified genetic variants plausibly accounting for SRS. Coding SNVs were identified in genes including CDKN1C, IGF2, IGF1R and ORC1. Maternal-effect variants were found in mothers of five participants, including two participants with imprinting disturbance and one with multilocus imprinting disorder. Two regions of homozygosity were suggestive of UPD involving imprinted regions implicated in SRS and Temple syndrome, and three plausibly pathogenic CNVs were found, including a paternal deletion of PLAGL1. In 48 participants with no plausible pathogenic variant, unbiased analysis of SNVs detected a potential association with STX4.

CONCLUSION

WGS analysis can detect UPD, CNV and SNV and is potentially a valuable addition to diagnosis of SRS and related growth-restricting disorders.

Floating-Harbor Syndrome Treated With Recombinant Human Growth Hormone: A Case Report and Literature Review

Introduction: We aimed to summarize the clinical characteristics of Floating-Harbor syndrome (FHS) and the effect of recombinant human growth hormone (rhGH) to increase height. Methods: The clinical manifestations, gene sequencing results, treatment, and regression of one child with FHS were reported at the Department of Pediatrics, General Hospital of Tianjin Medical University, in July 2020. PubMed was searched using the keyword "Floating-Harbor Syndrome" up to March 2021 to obtain clinical information on children with FHS for review. Results: The child, who was a male aged 6 years and 9 months, presented to the clinic with main complaints of delayed language development since childhood and a short stature for 4 years. The child's short stature, peculiar facial features, delayed language development, and delayed bone development were considered alongside genetic testing and Sanger sequencing to verify the results. A heterozygous mutation (c.7401delC; p.Ile2468Phefs^*7) was identified in exon 34 of the SRCAP gene, which was a frameshift mutation, and Sanger verification showed that neither parent had this mutation. The child was administered subcutaneous injection of rhGH (0.13 U/kg/day) and was followed up regularly. At the time of writing, the child had been treated for 6 months and was 7 years and 3 months old with a height of 106.3 cm (-3.69 SDS), which was a height increase of 6.3 cm. The patient did not complain of discomfort during treatment and presented normal laboratory tests results. Twenty-two children with FHS treated with rhGH were included in the literature review, and most of these patients demonstrated an increase in height SDS without adverse effects. Conclusion: Short stature, delayed skeletal maturation, impaired language expression, intellectual deficits, and peculiar facial features are the main clinical features of FHS. rhGH can be used as a treatment to increase height in patients with FHS, but its effectiveness and safety still need to be monitored in larger sample sizes over longer periods of time.

Novel Findings in Floating-Harbor Syndrome and a Mini-Review of the Literature

Floating-Harbor syndrome (FHS) is a rare autosomal dominant genetic disorder characterized by proportionate short stature with delayed bone maturation, lack of expressive language, and distinctive facial features including a large nose, long eyelashes, deeply set eyes, and triangular face. Mutations in the SRCAP gene cause truncated SNF2-related CREBBP activator protein (SRCAP) and lead to FHS. SRCAP is one of several proteins that act as coactivator for the CREB-binding protein which is associated with Rubinstein-Taybi syndrome (RSTS). This condition likely explains the phenotypic overlap between FHS and RSTS. Herein, we report on a patient with FHS who also had dystrophic toenails, preauricular skin tag, and nasolacrimal duct obstruction which is also defined in patients with RSTS. In summary, the fact that especially nasolacrimal duct obstruction has also been observed in RSTS reinforces the idea that this finding is one of the features of FHS. Assessment of the lacrimal system and examination of skin and nails should be suggested in patients with FHS.