NFIC-related disorder represents a novel neurodevelopmental syndrome characterized by intellectual disability and macrocephaly, highlighting the importance of NFIC dosage supporting a mirror-syndrome model.
Abstract
Nuclear factor I (NFI) transcription factors regulate neural stem and progenitor differentiation during brain development. While NFIA, NFIB, and NFIX are linked to neurodevelopmental disorders, the role of NFIC (MIM: 600729) in human disease remains unclear. This study aimed to determine whether NFIC contributes to a neurodevelopmental syndrome, define its phenotype, and assess dosage-dependent effects. We established the first cohort of 11 individuals, including NFIC deletions and single nucleotide variants. Genotype-phenotype correlations, including critical region mapping, were performed. Murine data and bioinformatics were integrated to explore underlying pathomechanisms. We report 11 individuals with NFIC variants, including four with de novo SNVs and seven with deletions encompassing the gene, of whom nine have not been previously reported. A core phenotype of syndromic intellectual disability and macrocephaly was delineated. Opposing cranial phenotypes relative to proximal 19p13.3 duplication cases support a dosage-sensitive effect and a mirror-syndrome model. NFIC-related disorder represents a novel neurodevelopmental syndrome characterized by intellectual disability and macrocephaly, highlighting the importance of NFIC dosage supporting a mirror-syndrome model.
Current knowledge on the genotypic and phenotypic spectra of SET-NDD is expanded, and pinpoints a smaller 9q34.11 critical region excluding upstream NDD-associated genes, STXBP1 and SPTAN1, implicating SET as a significant NDD-associated gene.
Angelo Condell, Elaine Zhang, Tim Sikora et al.· Clinical Genetics· 0 citations
This case expands the clinical spectrum associated with RFX3 variants, supporting a potential role in IESS and early neurodevelopmental disruption, and highlights the relevance of including RFX3 in the genetic evaluation of patients with IESS and co-occurring neurodevelopmental disorders.
Graziana Ceraolo, Giulia Spoto, M. Trivisano et al.· International Journal of Mol...· 0 citations
BACKGROUND
Trio Rho guanine nucleotide exchange factor (TRIO) encodes the guanine nucleotide exchange factor (GEF) for RHOA and RAC1 GTPases, which plays a critical role in neurodevelopment. Pathogenic variants in the TRIO gene are predominantly associated with two autosomal dominant neurodevelopmental disorders: intellectual developmental disorder 44 with microcephaly (MRD44) and intellectual developmental disorder 63 with macrocephaly (MRD63). However, the genotype-phenotype correlation of TRIO-related disorders and the impacts of TRIO variants on early-life disease progression remain unclear.
METHODS
In this study, we recruited a male infant with developmental delay and macrocephaly and chronologically detailed his growth from birth. Whole-exome sequencing was performed to identify genetic variants; three-dimensional protein modeling was employed to assess the pathogenicity of these variants, and previously reported TRIO variants were summarized.
RESULT
We identified a novel TRIO missense variant (NM_007118.4: c.7738 A > T, p.I2580F; chr5:14492781 A > T/hg19) in the patient, and the variant was positioned in the second Src homology 3 (SH3) domain. Bioinformatic and three-dimensional protein modeling evidence all support the p.I2580F variant as likely pathogenic. Additionally, we systematically collated and summarized previously reported TRIO gene variants.
CONCLUSION
Our findings broaden the variant landscape of TRIO, establish a correlation between macrocephaly and TRIO variants within the second SH3 domain, provide the first detailed growth chart for a patient with TRIO-associated macrocephaly, and deepen our understanding of developmental impairments attributed to TRIO variants.
Siyuan Zhang, Jie-Yuan Jin, Lei Zeng et al.· BMC Medical Genomics· 0 citations
Purpose: Neurofibromatosis type 2-related schwannomatosis (NF2-SWN) is an autosomal dominant tumor syndrome with complete penetrance and variable expressivity. Underlying patterns of disease burden and severity are largely unexplained. Methods: We comprehensively phenotyped 168 NF2-SWN patients over a mean duration of 4.5 years. We used a custom sequencing panel of NF2 and schwannomatosis genes to identify germline (n=166) and somatic variants in tumors (n=37). An optimized composite severity (CSS) score based on clinical and radiological data was created to analyze the effect of genetic variants on phenotype. Results: We found significant variable expressivity not explainable by demographic variables. Germline variants included premature termination (42%), splice-site (18%), and large deletions (16%). The CSS successfully predicted worsening clinical function in patients. Unsupervised clustering of clinical data revealed distinct phenotypic clusters that corresponded to CSS. Mosaicism, however, was not associated with CSS or any other disease severity marker. CSS was significantly associated with germline variant location along the NF2 locus. Specifically, FERM-F1 and the -helical variants were associated with increased disease severity. Within tumors, germline variants with severe effects on merlin acquired milder somatic second-hits at the NF2 locus. Conclusion: We identified a second-hit modifier to the Mendelian first-hit: severe germline variants were associated with milder somatic variants, and vice versa. This phenomenon partly explains the variable expressivity in NF2-SWN.
N. Ravindra, David T. Asuzu, Emma C. Celano et al.· medRxiv· 0 citations
PPP1R21-related neurodevelopmental disorder (PPP1R21-NDD) is an ultra-rare autosomal-recessive encephalopathy caused by dysfunction of the Five-subunit Endosomal Rab5 and RNA/ribosome intermediarY (FERRY) complex. To delineate the clinical, neuroimaging, and molecular spectrum of PPP1R21-NDD and outline diagnostic and research priorities. Targeted searches of PubMed, EMBASE, Scopus, Web of Science, and Google Scholar through January 2026 were performed. Eligible reports included molecularly confirmed biallelic PPP1R21 cases and related functional studies. Two researchers independently extracted individual-level data following narrative review quality criteria. Twenty-five individuals from 21 families harbored 17 distinct variants (15 loss-of-function, 2 missense), all homozygous, reflecting high consanguinity. Profound global developmental delay/intellectual disability was universal; hypotonia near-universal (22/25, 88%). Ambulation was delayed and ataxic when achieved; expressive language was minimal or absent. A recognizable coarse facial gestalt was observed with thick eyebrows, broad nasal bridge, thick lips, and low-set ears. Systemic features included feeding dysfunction and respiratory morbidity requiring gastrostomy or tracheostomy in severe cases. Mortality was 17% (4/24). Neuroimaging showed callosal thinning, white-matter volume loss, ventricular enlargement, and vermian hypoplasia. Patient fibroblasts showed delayed transferrin clearance and elevated proteasome activity, suggesting endosomal dysfunction and proteasome hyperactivation. PPP1R21-NDD is a severe recessive encephalopathy with a convergent phenotype and evidence of endo-lysosomal dysfunction. Diagnosis should be pursued with exome or genome sequencing in patients with characteristic clinical and neuroimaging features, particularly in consanguineous families. Research priorities include natural history studies, standardized magnetic resonance imaging (MRI) protocols, neural disease models, and therapeutic strategies targeting endosomal trafficking.
F. Comisi, G. Di Pasquale, A. Comisi et al.· Neurogenetics· 0 citations
The findings expand the evidence that pathogenic MECP2 variants can produce neurological phenotypes distinct from classic RTT, including mild neurodevelopmental impairment without regression, and predominantly cerebellar or spastic-ataxic manifestations associated with limited cognitive involvement.
Camilla Meossi, Alessandro De Falco, Deianira Rinaldi et al.· Journal of Neurology· 0 citations