I have a question about abbreviations in english, especially abbreviations that do not use full-stops (for example NATO, USA, DNA, RNA).
When using them in a written document where the phrase implies a plural for the abbreviation, is there a "s" appended to the abbreviation or not ?
For example in genetic the abbreviation for Quantitative Trait Loci is QTL. ON a genetic map several of those can be located. therefore you have regularly sentences like : Several QTL have been detected. So is it correct to write "QTL" or should I write "QTLs" ? Independently of the fact that "Loci" is already a plural
Thank you very much in advance for any help
Brendel, in my opinion an abbreviation such as the one given in your example should be follwed by an 's'. Although it doesn't seem to make logical sense, to add an 's' to QTL would be a good way of ensuring that other readers knew you were using the plural.
Certainly, the UK media also place an 'apostrophy s' after such acronyms as NATO, USA, etc to denote for instance action taken by these organisations.
Hope this helps.