ABSTRACT
Nucleotide repeat expansion is one of the common causes for neurodegenerative disorders. Polyglycine diseases are a newly defined neuro- and muscle- degenerative disease spectrum characterized by CGG trinucleotide repeat expansions, generation and aggregation of aberrant polyglycine protein, and formation of intranuclear inclusions. To date, the aggregation of pathogenic polyglycine protein has been proved in fragile X-associated tremor/ataxia syndrome and neuronal intranuclear inclusion disease. In recent years, the case load of these diseases grows rapidly with the increasing awareness and developing genetic testing technologies. This article aims to systematically review the recent progress in polyglycine diseases, and probe into their pathogenic mechanisms as well as clinical concerns.