Phenotype of ST3GAL3 deficient patients: A case and review of the literature

Human genetic defects of sphingolipid synthesis

Sphingolipids are ubiquitous lipids, present in the membranes of all cell types, the stratum corneum and the circulating lipoproteins. Autosomal recessive as well as dominant diseases due to disturbed sphingolipid biosynthesis have been identified, including defects in the synthesis of ceramides, sphingomyelins and glycosphingolipids. In many instances, these gene variants result in the loss of catalytic function of the mutated enzymes. Additional gene defects implicate the subcellular localization of the sphingolipid-synthesizing enzyme, the regulation of its activity, or even the function of a sphingolipid-transporter protein. The resulting metabolic alterations lead to two major, non-exclusive types of clinical manifestations: a neurological disease, more or less rapidly progressive, associated or not with intellectual disability, and an ichthyotic-type skin disorder. These phenotypes highlight the critical importance of sphingolipids in brain and skin development and homeostasis. The present article reviews the clinical symptoms, genetic and biochemical alterations, pathophysiological mechanisms and therapeutic options of this relatively novel group of metabolic diseases.

Identification of Risk Genes for Attention-Deficit/Hyperactivity Disorder During Early Human Brain Development

OBJECTIVE

Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder with high heritability. A total of 27 genome-wide significant loci for ADHD were previously identified through genome-wide association studies (GWASs), but the identification of risk genes that confer susceptibility to ADHD has remained largely unexplored.

METHOD

As ADHD is a neurodevelopmental disorder, we integrated human brain prenatal gene and transcript expression weight data (n = 120) and ADHD GWAS summary statistics (n = 225,534; 38,691 cases and 186,843 controls) to perform a transcriptome-wide association study (TWAS) by FUSION (an analytic suite).

RESULTS

Our analysis identified 10 genes, including LSM6, HYAL3, METTL15, RPS26, LRRC37A15P, RP11-142I20.1, ABCB9, AP006621.5, AC000068.5, and PDXDC1, that are significantly associated with ADHD, along with 8 transcripts of 7 genes. We also conducted TWAS analysis using CommonMind Consortium (CMC) adult brain gene and gene-splicing expression weights (n = 452), which highlighted several risk genes that showed associations with ADHD in both prenatal and postnatal stages, such as LSM6 and HYAL3.

CONCLUSION

Overall, our TWAS of ADHD, by integrating human prenatal brain transcriptome and ADHD GWAS results, uncovered the cis-effects of gene/transcript regulation that are predicted to be associated with ADHD. By combining colocalization and FOCUS fine-mapping analysis, we further unraveled potential causal candidate risk genes. The risk genes/transcripts that we identified in this study can serve as a valuable resource for further investigation of the disease mechanisms underlying ADHD.

Putting a cap on the glycome: Dissecting human sialyltransferase functions

Human glycans are capped with sialic acids and these nine-carbon sugars mediate many of the biological functions and interactions of glycans. Structurally diverse sialic acid caps mark human cells as self and they form the ligands for the Siglec immune receptors and other glycan-binding proteins. Sialic acids enable host interactions with the human microbiome and many human pathogens utilize sialic acids to infect host cells. Alterations in sialic acid-carrying glycans, sialoglycans, can be found in every major human disease including inflammatory conditions and cancer. Twenty sialyltransferase family members in the Golgi apparatus of human cells transfer sialic acids to distinct glycans and glycoconjugates. Sialyltransferases catalyze specific reactions to form unique sialoglycans or they have shared functions where multiple family members generate the same sialoglycan product. Moreover, some sialyltransferases compete for the same glycan substrate, but create different sialic acid caps. The redundant and competing functions make it difficult to understand the individual roles of the human sialyltransferases in biology and to reveal the specific contributions to pathobiological processes. Recent insights hint towards the existence of biosynthetic rules formed by the individual functions of sialyltransferases, their interactions, and cues from the local Golgi environment that coordinate sialoglycan biosynthesis. In this review, we discuss the current structural and functional understanding of the human sialyltransferase family and we review recent technological advances that enable the dissection of individual sialyltransferase activities.

Ethical Considerations and Equipoise in Cancer Surgery

The changing landscape of cancer surgery requires ongoing consideration of ethical issues to ensure patient-centered care and fair access to treatments. With technological advancements and the global expansion of surgical interventions, healthcare professionals must navigate complex ethical dilemmas related to patient autonomy, informed consent, and the impact of new technologies on the physician-patient relationship. Additionally, ethical principles and decision-making in oncology, especially in the context of genetic predisposition to breast cancer, highlight the importance of integrating patient knowledge, preferences, and alignment between goals and treatments. As global surgery continues to grow, addressing ethical considerations becomes crucial to reduce disparities in access to surgical interventions and uphold ethical duties in patient care. Furthermore, the rise of digital applications in healthcare, such as digital surgery, requires heightened awareness of the unique ethical issues in this domain. The ethical implications of using artificial intelligence (AI) in robotic surgical training have drawn attention to the challenges of protecting patient and surgeon data, as well as the ethical boundaries that innovation may encounter. These discussions collectively emphasize the complex ethical issues associated with surgical innovation and underscore the importance of upholding ethical standards in the pursuit of progress in the field. In this study, we thoroughly analyzed previous scholarly works on ethical considerations and equipoise in the field of oncological surgery. Our main focus was on the use of AI in this specific context.

Glycosphingolipids in congenital disorders of glycosylation (CDG)

Congenital disorders of glycosylation (CDG) are a large family of rare disorders affecting the different glycosylation pathways. Defective glycosylation can affect any organ, with varying symptoms among the different CDG. Even between individuals with the same CDG there is quite variable severity. Associating specific symptoms to deficiencies of certain glycoproteins or glycolipids is thus a challenging task. In this review, we focus on the glycosphingolipid (GSL) synthesis pathway, which is still rather unexplored in the context of CDG, and outline the functions of the main GSLs, including gangliosides, and their role in the central nervous system. We provide an overview of GSL studies that have been performed in CDG and show that abnormal GSL levels are not only observed in CDG directly affecting GSL synthesis, but also in better known CDG, such as PMM2-CDG. We highlight the importance of studying GSLs in CDG in order to better understand the pathophysiology of these disorders.

Clinical report and genetic analysis of a Chinese patient with developmental and epileptic encephalopathy associated with novel biallelic variants in the ST3GAL3 gene

BACKGROUND

Defects in the Golgi enzyme beta-galactoside-alpha-2,3-sialyltransferase-III (ST3Gal-III) caused by biallelic ST3GAL3 gene variants are associated with human neurodevelopmental disorders. Although ST3GAL3 gene variants have been linked to developmental and/or epileptic encephalopathy 15 (DEE15), their presence has only been reported in nine patients; however, the real frequency may be masked by insufficient screening.

METHODS

Phenotypic information was collected from a male patient with severe psychomotor developmental delay and epileptic seizures, and genetic testing was done using whole exome sequencing. A molecular dynamics simulation analysis was performed to assess the potential impacts of the identified ST3GAL3 variants on the ST3Gal-III protein function, and a literature review was conducted to compare this case with previously described cases and assess disease manifestation and genetic characteristics.

RESULTS

The patient inherited compound heterozygous ST3GAL3 gene variants, NM_006279.5:c.809G>A (p.Arg270Gln) and c.921dupG (p.Thr308fs*8). Neither variant had been previously reported in the general population. The p.Arg270Gln variant disrupted a hydrogen bond in the simulated ST3Gal-III protein structure. Among 25 patients with ST3GAL3 gene defects, eight ST3GAL3 gene variants were identified, and five variants had DEE signs.

CONCLUSION

Patients with DEE15 may have novel ST3GAL3 gene variants, and this study may be the first clinical report of their occurrence in a Chinese patient. These variants should be considered when evaluating patients presenting with unexplained early-onset epileptic encephalopathy, severe developmental delay, and/or intellectual disability.

Epigenetics applied to child and adolescent mental health: Progress, challenges and opportunities

Background

Epigenetic processes are fast emerging as a promising molecular system in the search for both biomarkers and mechanisms underlying human health and disease risk, including psychopathology.

Methods

In this review, we discuss the application of epigenetics (specifically DNA methylation) to research in child and adolescent mental health, with a focus on the use of developmentally sensitive datasets, such as prospective, population-based cohorts. We look back at lessons learned to date, highlight current developments in the field and areas of priority for future research. We also reflect on why epigenetic research on child and adolescent mental health currently lags behind other areas of epigenetic research and what we can do to overcome existing barriers.

Results

To move the field forward, we advocate for the need of large-scale, harmonized, collaborative efforts that explicitly account for the time-varying nature of epigenetic and mental health data across development.

Conclusion

We conclude with a perspective on what the future may hold in terms of translational applications as more robust signals emerge from epigenetic research on child and adolescent mental health.

Epilepsy and Cognitive Impairment in Childhood and Adolescence: A Mini-Review

Managing epilepsy in people with an intellectual disability remains a therapeutic challenge and must take into account additional issues such as diagnostic difficulties and frequent drug resistance. Advances in genomic technologies improved our understanding of epilepsy and raised the possibility to develop patients-tailored treatments acting on the key molecular mechanisms involved in the development of the disease. In addition to conventional antiseizure medications (ASMs), ketogenic diet, hormone therapy and epilepsy surgery play an important role, especially in cases of drugresistance. This review aims to provide a comprehensive overview of the mainfactors influencing cognition in children and adolescents with epilepsy and the main therapeutic options available for the epilepsies associated with intellectual disability.

A combination of two novels homozygous FCSK variants cause disorder of glycosylation with defective fucosylation: New patient and literature review

Pathogenic variants in FCSK cause Congenital Disorder of Glycosylation with Defective Fucosylation-2 (FCSK-CDG; MIM: 618,324). It is a rare autosomal recessive genetic disease caused by defects in the L-fucose kinase, which is necessary for the fucose salvage pathway. Herein, we report two novel variants in an Iranian patient, the fourth individual with FCSK-CDG described in the literature. Two homozygous variants in FCSK (rs376941268; NM_145059.3: c.379C > A, p. Leu127Met and rs543223292; NM_145059.3: c.394G > C, p. Asp132His) were identified in the proband. Sanger sequencing conducted on his unaffected parents revealed that they were heterozygous for the same variants. The proband, a four-and-a-half year old Iranian male born to consanguineous parents, manifested Intellectual disability, growth delay, ophthalmic abnormalities, seizures, speech disorder, and feeding difficulties.

Phenotypic spectrum of autosomal recessive Keratitis-Ichthyosis-Deafness Syndrome (KIDAR) due to mutations in AP1B1

Inborn errors in copper metabolism result in a diverse set of abnormalities such as Wilson disease and MEDNIK syndrome. Homozygous pathogenic variants in AP1B1 lead to KIDAR (Keratitis-Ichthyosis-Deafness Syndrome). The main phenotypic features of KIDAR are ichthyosis, keratitis, erythroderma, and progressive hearing loss accompanied by developmental delay and failure to thrive. Herein, we describe a six-and-a-half-year-old boy with KIDAR caused by a novel pathogenic variant in AP1B1 (NM_001127.4:c.1263C > A, p.Tyr421*). The proband presented with ichthyosis, erythroderma, palmoplantar keratoderma, hearing loss, and corneal scarring. He also had hypotonia, global developmental delay, and photophobia. Lastly, we review all of the previously reported cases and the clinical features associated with KIDAR.

A novel non-sense mutation in TDP2 causes spinocerebellar ataxia autosomal recessive 23 accompanied by bilateral upward gaze; report of a case and review of the literature

Pathogenic mutations in TDP2, encoding tyrosyl DNA phosphodiesterase 2, cause Spinocerebellar Ataxia autosomal recessive 23 (SCAR23). It is a rare autosomal recessive disorder and mainly has been reported in the European population. Thus far, merely eight patients harboring four TDP2 variants have been reported in the literature. In this study, a novel pathogenic variant (NM_016614: c.4G > T, p.Glu2*) was identified by Whole-Exome and confirmed by Sanger sequencing. The proband has both intellectual and developmental delay, dysphasia, elbow contracture, and upward gaze. The elbow contracture has not been previously described in previous SCAR23 cases. Lastly, we briefly review the phenotypic features of the patients with SCAR23 in the literature.

A novel frameshift pathogenic variant in ST3GAL5 causing salt and pepper developmental regression syndrome (SPDRS): A case report

GM3 synthase deficiency is associated with salt and pepper developmental regression syndrome (SPDRS), a rare genetic disorder. Herein, we report the first Iranian patient with SPDRS. We detected a novel pathogenic variant of ST3GAL5 (NM_003896.4: c.1030_1031del, p.Ile344Cysfs*11). The proband had intellectual disability (ID), failure to thrive, cerebral atrophy, microcephaly, and atonic seizures. The main future challenge proceeding from the results of this study is the prenatal detection of the newly discovered variant; the next step would involve further studies to elucidate the phenotypic spectrum of SPDRS and detect new variants that could cause symptoms ranging from mild to severe.