The clinical manifestations of neuronal intranuclear inclusion disease (NIID) are heterogeneous, and the premortem diagnosis is mainly based on skin biopsy findings. Abnormal GGC repeat expansions in was recently identified in familial and sporadic NIID. The comparison of diagnostic value between abnormal GGC repeat expansions of and skin biopsy has not been conducted yet. In this study, skin biopsy was performed in 10 suspected adult NIID patients with clinical and imaging manifestations, and GGC repeat size in was also screened by repeat primed-PCR and GC-rich PCR. We found that five cases had ubiquitin-immunolabelling intranuclear inclusion bodies by skin biopsy, and all of them were identified with abnormal GGC repeat expansions in , among whom four patients showed typical linear hyperintensity at corticomedullary junction on DWI. Five (5/10) NIID patients were diagnosed by combination of gene detection, skin biopsy or combination of , and typical MRI findings. The diagnostic performance of gene detection was highly consistent with that of skin biopsy ( = 1). The unexplained headache was firstly reported as a new early phenotype of NIID. These findings indicate that gene detection is needed to be a supplement in the diagnose flow of NIID and also may be used as an alternative method to skin biopsy especially in Asian population.