The (CCTTT)(n)locus showed a trend for RA association in the case-control study, however, stratification data by Class II status did not yield significant effect and overall, the family study showed no significant association nor linkage for any of the markers under study using TDT and non-parametric linkage respectively.
We have implemented the combined sib-TDT and TDT, in addition to parametric and non-parametric linkage methods, to investigate the candidate genes of the interleukin-1 (IL-1) gene cluster on chromosome region 2q13, since IL-1 is an important cytokine in the control of the inflammatory response that is central to RA pathology.