[Neuronal intranuclear inclusion disease (NIID)]

Area of Science:

• Neurology
• Genetics
• Pathology

Background:

• Neuronal intranuclear inclusion disease (NIID) is a progressive neurodegenerative disorder.
• Historically diagnosed via autopsy, recent advances have improved diagnostic accessibility.
• Increased case identification follows the 2011 report on skin biopsy utility.

Purpose of the Study:

• To summarize the diagnostic advancements and clinical presentations of NIID.
• To highlight the importance of NIID in differential diagnoses for leukoencephalopathy and neuropathy.
• To emphasize the necessity of integrated diagnostic approaches for NIID.

Main Methods:

• Review of recent literature on NIID diagnosis and genetics.
• Analysis of clinical and imaging findings in NIID patients.
• Discussion of diagnostic criteria including skin biopsy and genetic testing.

Main Results:

• The genetic cause of NIID is linked to GGC repeat expansions in the NOTCH2NLC gene, identified in 2019.
• NIID presents with two main phenotypes: cognitive dysfunction with leukoencephalopathy, or limb weakness.
• Skin biopsy and genetic testing are crucial for accurate NIID diagnosis.

Conclusions:

• NIID requires inclusion in the differential diagnosis for leukoencephalopathy and neuropathy.
• Combined skin biopsy and genetic testing are essential for accurate NIID diagnosis.
• Further pathological elucidation is needed, facilitated by improved diagnostic methods.