KIR3DL1 and systemic sclerosis: Regarding KIR genotypes, the Bx genotype was more frequent in SSc patients; in particular, the Bx genotype with ID 19 (according to the Allele Frequency Database [8]) was found only in SSc patients, whereas the AA genotype with ID 1 (according to the Allele Frequency Database [8]) was associated with lower risk to SSc development.