KRT1 and systemic lupus erythematosus: Hypothesizing that the haplotypes of KRT1-Del (low risk) and KRT1-MU (high risk) haplotypes have opposite effects to associate with SLE and SSc as above, the patients were further classified into three sub-groups according to the individuals having Del and no MU genotype (Del+/MU-, low risk alone), having no Del but with MU genotype (Del-/MU+, high risk alone), having both haplotypes (Del+/MU+, opposite risk together) and none of them (Del-/MU-) for a deep analysis (Table 4).