TPO and ataxia telangiectasia: Interestingly, a significant correlation between 25(OH) vitamin D and TPO-Ab (r = −0.27, p = 0.03) and FT3 (r = 0.35, p = 0.006) has been found in subjects with AT while no correlation was found between 25(OH) vitamin D levels and TG-Ab (r = −0.15, p = 0.25), TSH (r = −0.014, p = 0.09) and FT4 (r = 0.13, p = 0.32).