In order to gain further insight into the potential function of CXORF21, we utilised high-throughput affinity-purification mass spectrometry data from BioPlex32 and revealed a high confidence (quantitative score: 0.999) protein–protein interaction between CXORF21 and SLC15A4, encoded by the SLE susceptibility gene SLC15A4 (rs1059312; PMETA = 1.48 × 10−13; OR = 1.17)15. Here, SLC15A4 is linked to systemic lupus erythematosus.