Porto-sinusoidal vascular disorder (PSVD) is a rare liver disease. The pathophysiological mechanisms underlying the development of PSVD are unknown. Isolated cases of PSVD associated with gene mutations have been reported, but no overview is available. Therefore, we performed an extensive literature search to provide a comprehensive overview of gene mutations associated with PSVD. We identified 34 genes and 1 chromosomal abnormality associated with PSVD in the literature, and we describe here 1 additional gene mutation ( TBL1XR1 mutation, leading to Pierpont syndrome). These gene mutations are associated either with extrahepatic organ involvement as part of syndromes (Adams-Oliver, telomere biology disorders, retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations, immune deficiencies, cystic fibrosis, cystinosis, Williams-Beuren, Turner, Pierpont) or with isolated PSVD ( KCNN3 , DGUOK , FOPV , GIMAP5 , FCHSD1 , TRMT5 , HRG gene mutations). Most of the cases were revealed by signs or complications of portal hypertension. When analyzing the cell types in which these genes are expressed, we found that these genes are predominantly expressed in immune cells, suggesting that these cells may play a more important role in the development of PSVD than previously thought. In addition, pathway analyses suggested that there may be 2 types of PSVD associated with gene mutations: those resulting directly from morphogenetic abnormalities and those secondary to immune changes.

Transducin β-like 1 X-linked receptor 1 (TBL1XR1) protein is an important component of NCoR/SMRT complex. The variants of TBL1XR1 are associated with Pierpont syndrome (PS) and developmental delay (DD). This study aimed to discover new TBL1XR1 variants, their clinical manifestations, and protein-level changes. Whole-exome sequencing was used to identify patients with TBL1XR1 variants in 2024. Minigene assay was used to investigate specific splice site, which was further validated by Sanger sequencing. Structural changes in the TBL1XR1 protein were analyzed using PyMOL and molecular dynamics (MD) simulations. Potential binding partners were predicted via Genecards, STRING, and Cytoscape, while molecular docking was employed to assess how variants affect protein complex interactions. Two novel TBL1XR1 variants (c.1048-8_1049del and c.865-7A>G) were identified in two patients. Patient 1 exhibits global developmental delay (GDD), while patient 2 displays with facial dysmorphism and autism spectrum disorder. c.865-7A>G is a non-canonical splicing variant causing abnormal mRNA splicing. SpliceAI and RDDC predicted its splicing pattern. Minigene analysis found a 6 bp (TCTCAG) insertion in mRNA, leading to two amino acid (SQ) insertion in the TBL1XR1 protein. Therefore, P2 was diagnosed with PS. Variant changed the local hydrogen bond network and electrostatic potential. MD simulations showed variant changed the conformation of TBL1XR1 protein. Protein–protein interaction analysis selected NCOR1 for docking with TBL1XR1. Their interaction was reduced after the insertion of SQ, which may contribute to the occurrence of PS. This study reported two patients manifesting with GDD and PS, which were identified with two novel variants of TBL1XR1 (c.1048-8_1049del, p.(N350X)) and (c.865-7A>G, p.K288_T289insSQ), respectively. c.865-7A>G variant might lead to PS by reducing its interaction with NCOR1. The online version contains supplementary material available at 10.1186/s40246-025-00877-9.

The TBL1XR1 gene (Transducin beta-like 1X-linked receptor 1) is responsible for encoding the TBL1XR1 protein, an important component of the NCoR and SMRT corepressor complexes. 48 missense variants of the TBL1XR1 gene have been reported, which are associated with various phenotypes of neurodevelopmental disorders, including West syndrome, Pierpont syndrome, and others. However, given the important role of TBL1XR1 in neurological diseases, it is still necessary to further explore the variation of TBL1XR1. In this study, we present two patients with distinct variants and phenotypes. Patient 1 exhibits global developmental delay, intellectual disability, delayed language development, and seizures. While patient 2 displays mild facial dysmorphism, significant developmental delay, feeding difficulties, and increased muscle tone. Through trio whole-exome sequencing, two novel pathogenic variants in the TBL1XR1 gene were identified: A heterozygous NM_024665.6:c.940G > T (p.Val314Phe) variant in patient 1 and a heterozygous NM_024665.6:c.1387G > T (p.Asp463Tyr) in patient 2. Discovery of these two novel variant sites expands the mutation spectrum associated with the TBL1XR1 gene.

TBL1XR1 encodes a F-box-like/WD40 repeat-containing protein that plays a role in transcription mediated by nuclear receptors and is a known genetic cause of neurodevelopmental disease of childhood (OMIM# 608628). Yet the developmental trajectory and progression of neurologic symptoms over time remains poorly understood. We developed and distributed a survey to two closed Facebook groups devoted to families of patients with TBL1XR1-related disorder. The survey consisted of 14 subsections focused upon the developmental trajectories of cognitive, behavioral, motor, and other neurological abnormalities. Data were collected and managed using REDCap electronic data capture tools. Caregivers of 41 patients with a TBL1XR1-related disorder completed the cross-sectional survey. All reported variants affecting a single amino acid, including missense mutations and in-frame deletions, were found in the WD40 repeat regions of Tbl1xr1. These are domains considered important for protein-protein interactions that may plausibly underlie disease pathology. The majority of patients were diagnosed with a neurologic condition before they received their genetic diagnosis. Language appeared most significantly affected with only a minority of the cohort achieving more advanced milestones in this domain. TBL1XR1-related disorder encompasses a spectrum of clinical presentations, marked by early developmental delay ranging in severity, with a subset of patients experiencing developmental regression in later childhood.

Transducin β-like 1 X-linked receptor 1 (mouse Tbl1xr1) or TBL1X/Y related 1 (human TBL1XR1), part of the NCoR/SMRT corepressor complex, is involved in nuclear receptor signaling. Variants in TBL1XR1 cause a variety of neurodevelopmental disorders including Pierpont syndrome caused by the p.Tyr446Cys variant. We recently reported a mouse model carrying the Tbl1xr1Y446C/Y446C variant as a model for Pierpont syndrome. To obtain insight into mechanisms involved in altered brain development we studied gene expression patterns in the cortex of mutant and wild type (WT) mice, using RNA-sequencing, differentially expressed gene (DEG) analysis, gene set enrichment analysis (GSEA), weighted gene correlation network analysis (WGCNA) and hub gene analysis. We validated results in mutated mouse cortex, as well as in BV2 and SK-N-AS cell lines, in both of which Tbl1xr1 was knocked down by siRNA. Two DEGs (adj.P. Val < 0.05) were found in the cortex, Mpeg1 (downregulated in mutant mice) and 2900052N01Rik (upregulated in mutant mice). GSEA, WGCNA and hub gene analysis demonstrated changes in genes involved in ion channel function and neuroinflammation in the cortex of the Tbl1xr1Y446C/Y446C mice. The lowered expression of ion channel genes Kcnh3 and Kcnj4 mRNA was validated in the mutant mouse cortex, and increased expression of TRIM9, associated with neuroinflammation, was confirmed in the SK-N-AS cell line. Conclusively, our results show altered expression of genes involved in ion channel function and neuroinflammation in the cortex of the Tbl1xr1Y446C/Y446C mice. These may partly explain the impaired neurodevelopment observed in individuals with Pierpont syndrome and related TBL1XR1-related disorders.