correction: in the legend of figure 2 of the article "the amyloid state and its association with protein misfolding diseases" (nature reviews molecular cell biology 15, 384–396, 2014), the sentence "the spacing between polypeptide chains along the fibril axis is constant to a good approximation even for very different polypeptide sequences, a generic property arising from the common inter-side chain hydrogen bonding constraints (orange line in part b)" incorrectly referred to 'inter-side chain' hydrogen bonding constraints. it should have referred to 'inter-main chain' hydrogen bonding constraints. this has been corrected online. the authors apologize for any confusion caused to readers.correction: in the legend of figure 2 of the article "the amyloid state and its association with protein misfolding diseases" (nature reviews molecular cell biology 15, 384–396, 2014), the sentence "the spacing between polypeptide chains along the fibril axis is constant to a good approximation even for very different polypeptide sequences, a generic property arising from the common inter-side chain hydrogen bonding constraints (orange line in part b)" incorrectly referred to 'inter-side chain' hydrogen bonding constraints. it should have referred to 'inter-main chain' hydrogen bonding constraints. this has been corrected online. the authors apologize for any confusion caused to readers.