Here are a couple of useful links for gene symbols:
Link to a paper from the BioScience journal giving rules for appropriate gene symbols --
http://www.ringneckdove.com/Wilmer's...ioscience.html and search for the section "Use of a standard of reference".
Link to Guidelines for Nomenclature of Genes, Genetic Markers, Alleles, and Mutations in Mouse and Rat -- http://www.informatics.jax.org/mgihome/nomen/gene.shtml. Sections 1 and 3 are the most useful parts.