Expansion of the Phenotypic Spectrum of TNRC6B-Related Neurodevelopmental Disorder in a Three-Generation Family with 22q13.1 Deletion

Background: TNRC6B encodes a core effector of the RNA-induced silencing complex and is essential for miRNA-mediated gene silencing. Pathogenic variants in TNRC6B have re-cently been associated with a neurodevelopmental disorder characterised by develop-mental delay, intellectual disability, and behavioural difficulties. Methods: We report a three-generation family with a 22q13.1 deletion encompassing TNRC6B. Clinical data were collected from medical records and family interviews, and the findings were compared with those of published cohorts. Results: Affected individuals presented with developmental delay, speech and language impairment, autism spectrum disorder, ADHD, oppositional defiant disorder, cranio-synostosis, joint laxity, clinodactyly, and cardiac valve anomalies. The father and paternal grandmother had learning difficulties and neurobehavioral features, while the proband exhibited a more severe phenotype. Conclusion: This report expands the phenotypic spectrum of TNRC6B-related neurode-velopmental disorder, highlighting craniosynostosis, joint and connective tissue features, and cardiac involvement. Our findings also underscore variable expressivity across gen-erations and emphasise the relevance of both copy-number and sequence variants in TNRC6B in patients with neurodevelopmental disorders.