Hexanucleotide repeat expansions, often in introns, are associated with at least two diseases, Frontotemporal dementia and/or amyotrophic lateral sclerosis (FTDALS, caused by expansions in the C9ORF72 gene) and Spinocerebellar ataxia 36 (SCA36, caused by expansions in the NOP56 gene). They may also may also cause susceptibility to asthma. The mechanisms by which these expansions cause disease is currently unknown, but it likely involves the production of dipeptide repeat proteins generated from the expanded hexanucleotide regions.

For stocks used to study hexanucleotide repeats, please see the FTDALS page.