Effects of long-term growth hormone therapy in a girl with Floating-Harbor syndrome

Clinical application of prospective whole-exome sequencing in the diagnosis of genetic disease: Experience of a regional disease center in South Korea

INTRODUCTION

Next-generation sequencing helps clinicians diagnose patients with suspected genetic disorders. The current study aimed to investigate the diagnostic yield and clinical utility of prospective whole-exome sequencing (WES) in rare diseases.

METHODS

WES was performed in 92 patients who presented with clinical symptoms suggestive of genetic disorders. The WES data were analyzed using an in-house developed software. The patients' phenotypic characteristics were classified according to the human phenotype ontology.

RESULTS

WES detected 64 variants, 13 were classified as pathogenic, 26 as likely pathogenic, and 25 as variants of uncertain significance. In 57 patients with these variants, 30 were identified as causal variants. The diagnostic yield was higher in patients with abnormalities in joint mobility and skin morphology than in those with cerebellar hypoplasia/atrophy, epilepsy, global developmental delay, dysmorphic features/facial dysmorphisms, and chronic kidney disease/abnormal renal morphology.

CONCLUSION

In this study, a WES-based variant interpretation system was employed to provide a definitive diagnosis for 28.3% of the patients suspected of having genetic disorders. WES is particularly useful for diagnosing rare diseases with symptoms that affect more than one system, when targeted genetic panels are difficult to employ.

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.

Empty Sella Syndrome Associated with Growth Hormone Deficiency: the First Case Report of Weiss-Kruszka Syndrome

Weiss-Kruszka syndrome (WSKA), caused by heterozygous loss-of-function variants in ZNF462 gene, is a recently described and extremely rare genetic disorder. The main phenotypes include characteristic craniofacial features, ptosis, dysgenesis of the corpus callosum, and neurodevelopmental impairment. We report the first Korean boy with molecularly confirmed WSKA presenting with an atypical manifestation. A 16-year-old boy with a history of bilateral ptosis surgery presented with short stature (-3.49 standard deviation score) and delayed puberty. The patient showed characteristic craniofacial features including an inverted triangular-shaped head, exaggerated Cupid's bow, arched eyebrows, down-slanting palpebral fissures, and poorly expressive face. He had a mild degree of intellectual disability and mild hypotonia. Endocrine studies in the patient demonstrated complete growth hormone deficiency (GHD) associated with empty sella syndrome (ESS), based on a magnetic resonance imaging study for the brain that showed a flattened pituitary gland and cerebrospinal fluid space herniated into the sella turcica. To identify the genetic cause, we performed whole exome sequencing (WES). Through WES, a novel de novo heterozygous nonsense variant, c.4185del; p.(Met1396Ter) in ZNF462 was identified. This is the first case of WSKA accompanied by primary ESS associated with GHD. More clinical and functional studies are needed to elucidate this association.

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.