It is unlikely that the difference in haplotype 4 results is caused by fluctuation in control frequencies, as was previously noted with respect to observation of a protective haplotype in a study of the PTPN22 locus in Graves' disease [13], [17] – changes in both the control and case rs3811201 frequencies are evident between the Carlton et al [9] and the newly analysed data (Table 3). The gene discussed is PTPN22; the disease is Graves disease.