Adwords recently announced a change in their algorithm that help match ads with searches by accounting for misspellings and variations.
The goal of the update is to help match the ads with search users using exact and phrase matching options--this expansion will help show ads when people search for close variants. The variants will include singular and plural forms, acronyms, stemmings, abbreviations, and accents. The system will also work for exact match and phrase match keyword specifications.
In terms of Quality Score, Google will use exact keyword, and not close variants, to determine your Quality Score and first page bid estimate.