Neuronal Intranuclear Inclusion Disease Mechanisms and Diagnostic Techniques

Neuronal intranuclear inclusion disease (NIID) is a progressive neurodegenerative disorder defined by eosinophilic protein aggregates within the nuclei of neurons and multiple somatic cell types. Pathogenic expansions of trinucleotide repeats, most notably GGC motifs in the 5′ untranslated region of the NOTCH2NLC gene, underlie a spectrum of clinical manifestations ranging from dementia and parkinsonism to peripheral neuropathy and multisystem dysfunction. At the cellular level, expanded repeat transcripts are prone to form RNA foci and sequester RNA-binding proteins, while aberrant translation of polyglycine peptides contributes to intranuclear inclusions that impair nucleocytoplasmic transport, proteostasis and mitochondrial function. Neuroimaging frequently reveals a characteristic high-intensity signal along the corticomedullary junction on diffusion-weighted MRI, and systemic involvement may be detected by targeted skin or muscle biopsy demonstrating p62-positive inclusions. Advances in long-read sequencing and methylation profiling have refined the detection of repeat length, sequence interruptions and epigenetic modifications, thereby improving diagnostic sensitivity and elucidating factors that modulate penetrance and tissue specificity. Together, mechanistic insights and enhanced diagnostic modalities are informing earlier detection, more accurate genotype–phenotype correlations and the groundwork for targeted therapies.

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Neuronal Intranuclear Inclusion Disease Mechanisms and Diagnostic Techniques publication trend

The graph below shows the total number of articles in neuronal intranuclear inclusion disease mechanisms and diagnostic techniques across all publications each year (not limited to Nature Index journals).

Technical terms

Intranuclear inclusion: A proteinaceous aggregate within the cell nucleus that disrupts normal nuclear functions.

GGC repeat expansion: A trinucleotide sequence repetition in DNA that, when abnormally long, causes RNA toxicity and protein aggregation.

NOTCH2NLC: A human-specific gene containing GGC repeats whose pathogenic expansions are central to NIID.

Diffusion-weighted imaging (DWI): An MRI technique sensitive to water molecule movement, used to detect characteristic brain signal changes in NIID.

Long-read sequencing: A genome sequencing approach that generates extended DNA reads, enabling accurate characterisation of repeat expansions and methylation patterns.

References

1. NOTCH2NLC GGC intermediate repeat with serine induces hypermyelination and early Parkinson’s disease-like phenotypes in mice. Molecular Neurodegeneration (2024).
2. Expansion of Human-Specific GGC Repeat in Neuronal Intranuclear Inclusion Disease-Related Disorders. American Journal of Human Genetics (2019).
3. Re‐defining the clinicopathological spectrum of neuronal intranuclear inclusion disease. Annals of Clinical and Translational Neurology (2020).
4. Father-to-offspring transmission of extremely long NOTCH2NLC repeat expansions with contractions: genetic and epigenetic profiling with long-read sequencing. Clinical Epigenetics (2021).