Connectome Analysis in an Individual with SETD1B -Related Neurodevelopmental Disorder and Epilepsy

SETD1B variants associated with absence seizures

AIM

Exploring the association between SETD1B variants and absence seizures (ASs).

METHODS

We engaged a small cohort of four pediatric epilepsy patients with identified SETD1B variants and conducted a comprehensive review of 50 documented instances. Clinical profiles were meticulously compiled, and genetic screening was executed via trio-based whole-exome sequencing. Our literature survey centered on AS manifestations linked to SETD1B alterations, utilizing descriptive statistics for analysis.

RESULTS

The quartet of new cases presented with developmental impediments, cognitive deficits, and epileptic manifestations. Pathogenicity was established in the detected SETD1B variants. Among the 54 individuals, 26 (accounting for 48.1 %) presented with AS during the course of the disease. The median seizure onset age stood at 44.8 months, with a majority displaying cognitive challenges and autistic traits. Anti-epileptic drug therapies proved efficacious in 70.8 % of the instances. Notably, variants within the N-SET, SET, and post-SET domains of SETD1B were prevalent in 46.2 % of the AS-afflicted cohort.

DISCUSSION

Our findings accentuate the potential influence of SETD1B variants in AS pathogenesis, these variants may perturb neuronal excitability, possibly via modulation of histone methylation landscapes. The insights garnered here deepen our grasp of AS's genetic architecture.

CONCLUSION

Our study identified four novel SETD1B variants, highlighting that the importance of AS as part of the phenotype among individuals with SETD1B, demonstrated by 3 novel cases, and supported by review of the literature. Our findings also suggest that the SET domains may play a potential role in the pathogenesis of AS, providing a clue for future mechanistic research.

Epigenetic Mechanism of SETD1B-mediated Histone Methylation in Cognitive Impairment Induced by Sevoflurane Anesthesia in Neonatal Mice

Sevoflurane (Sev) anesthesia is associated with cognitive deficits and neurotoxicity. This study explores the epigenetic mechanism of SET domain containing 1B (SETD1B) in Sev-induced cognitive impairment in neonatal mice. Neonatal mice (C57BL/6, n = 72) were exposed to 3% Sev for 2 h per day at P6, 7, and 8, and the control neonatal mice were only separated from the mother for 2 h. The mice were divided into groups of 12 individuals, with an equal number of male and female mice in each group. Mice were intraperitoneally injected with adenovirus-packaged SETD1B overexpression vector. Behavioral tests (Morris water maze, open field test, T-maze, novel object recognition, etc.) were performed at P30. Mouse hippocampal neuronal cells were cultured in vitro. SETD1B, C-X-C motif chemokine receptor 4 (CXCR4), NLR family pyrin domain containing 1 (NLRP1), Cleaved Caspase1, and GSDMD-N expressions in hippocampal tissues or cells were determined by quantitative real-time polymerase chain reaction and Western blot. SETD1B and histone H3 lysine 4 methylation (H3K4me1, H3K4me2, and H3K4me3) enrichment on the CXCR4 promoter was analyzed by ChIP. Sev insulted cognitive impairment and diminished SETD1B expression in mouse hippocampal tissues. SETD1B overexpression mitigated cognitive impairment, enhanced H3K4me3 levels in hippocampal tissues, and restrained hippocampal neuronal pyroptosis. SETD1B increased CXCR4 expression by elevating the H3K4me3 level on the CXCR4 promoter, thereby curbing NLRP1/Caspase1-mediated hippocampal neuronal pyroptosis. To conclude, SETD1B enhances CXCR4 expression by elevating the H3K4me3 level on the CXCR4 promoter, thereby suppressing NLRP1/Caspase1-triggered hippocampal neuronal pyroptosis and alleviating Sev-induced cognitive impairment in neonatal mice.

Rare diseases of epigenetic origin: Challenges and opportunities

Rare diseases (RDs), more than 80% of which have a genetic origin, collectively affect approximately 350 million people worldwide. Progress in next-generation sequencing technology has both greatly accelerated the pace of discovery of novel RDs and provided more accurate means for their diagnosis. RDs that are driven by altered epigenetic regulation with an underlying genetic basis are referred to as rare diseases of epigenetic origin (RDEOs). These diseases pose unique challenges in research, as they often show complex genetic and clinical heterogeneity arising from unknown gene-disease mechanisms. Furthermore, multiple other factors, including cell type and developmental time point, can confound attempts to deconvolute the pathophysiology of these disorders. These challenges are further exacerbated by factors that contribute to epigenetic variability and the difficulty of collecting sufficient participant numbers in human studies. However, new molecular and bioinformatics techniques will provide insight into how these disorders manifest over time. This review highlights recent studies addressing these challenges with innovative solutions. Further research will elucidate the mechanisms of action underlying unique RDEOs and facilitate the discovery of treatments and diagnostic biomarkers for screening, thereby improving health trajectories and clinical outcomes of affected patients.