The frequency of the G allele in Bulgarian controls did not differ from that reported in other Europeans samples (13.8% compared to 17% for HapMap-CEU), and was very close to those observed in an Australian study (E.C. Nelson, personal correspondence) for general population controls (15.5% on N=1494) and controls from socioeconomically disadvantaged neighbourhoods (12.5% on N=531). There are no reference frequencies for this polymorphism in Bulgarian Romas, a population that is believed to have Indian origins (Gresham et al., 2001). In Romas, the observed frequency of the G allele (20.2%) was significantly different to that reported for Indians from the Kayastha and Brahmin castes of the Bengali-Hindu ethnic background sample (28%, χ2(1) = 35.68, p < 0.0001) (Deb et al., 2010), and from those reported in Tan et al. (47%, χ2(1) = 72.6, p < 0.0001) for an Indian sample (Tan et al., 2003).
