SLC22A4 and hematocrit: We hypothesized that SLC22A4 might be involved in genetic susceptibility of AITD through the transportation of small organic molecules (such as immune regulatory factors), and such involvement might be mediated by a SNP located in a RUNX1-binding sequence in SLC22A4 affecting the expression of SLC22A4. In this study we collected AITD pedigrees (GD pedigrees and HT pedigrees), genotyped rs3792876 and assess the genetic susceptibility of this SLC22A4 polymorphism to GD, HT and AITD in our Chinese Han populations.