Although many cases of head and neck paraganglioma are apparently sporadic (i.e. no known family history), clustering in families has long been recognized [1,2], and the search for susceptibility loci led to the mapping of two putative loci: PGL1-11q23 [2,3] and PGL2-11q13 [4]. This evidence concerns the gene SDHD and head and neck paraganglioma.