Polymorphism of keratin 1 associates with systemic lupus erythematosus and systemic sclerosis in a south Chinese population.

Both systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) diseases are related to the genetic and environmental factors, causing damage to the skin. The mutations of keratin 1 gene (KRT1) were reported to associate with skin diseases. The single-nucleotide polymorphism (SNP, rs14024) and the indel polymorphism (cds-indel, rs267607656), consisting mostly of the common haplotypes and could be used for genotyping of KRT1. We used the PCR with sequence specific primers (PCR-SSP) to determine the genotype of KRT1 in 164 SLE, 99 SSc patients, and 418 healthy controls. The results showed that the mutant with G at SNP rs14024 was associated with the high risk to SLE (p = 6.48×10-5) and SSc (p = 8.75×10-5), while the deletion allele at rs267607656 was associated with the low risk to SSc (p = 4.89×10-4) comparing to the normal controls. Haplogenotype, Del-/MU+ was associated with high susceptibility to SLE (OR = 1.87, p = 0.001) and SSc (OR = 2.29, p = 2.34×10-4). In contrast, the Haplogenotype Del+/MU- was associated with resistance to SLE (OR = 0.35, p = 6.24×10-5) and SSc (OR = 0.34, p = 0.001). This study demonstrates that the variations in KRT1 and the specific polymorphism of KRT1 in this Chinese Han population are associated with autoimmune diseases SLE and SSc. Typing KRT1 might be helpful to identify SLE and SSc patients.