I find The Cystic Fibrosis Mutation Database very useful. <a href="http://www.genet.sickkids.on.ca/cftr/app" rel="nofollow" target="_blank">http://www.genet.sickkids.on.ca/cftr/app</a> Like this table of most common CFTR mutations and prevalence in populations(data based on the screening of 43,849 CF chromosomes). <a href="http://www.genet.sickkids.on.ca/cftr/resource/Table1.html" rel="nofollow" target="_blank">http://www.genet.sickkids.on.ca/cftr/resource/Table1.html</a>