Notably, since the functional impact of rare and deleterious variants is likely to be greater when present as homozygote, 5 rare and deleterious homozygous variants (NCR3LG1, RAP1GAP, CHCHD5, HIPK2 and DIAPH2) were identified in the Chinese RA samples and absent in the controls (group 5 in Figure 1; Supplementary Table 3). This evidence concerns the gene RAP1GAP and rheumatoid arthritis.