Rheumatoid Arthritis and Primary Biliary Cirrhosis: Cause, Consequence, or Coincidence?

Table 1

Major susceptibility genes associated with primary biliary cirrhosis (PBC), as reported through genome-wide association studies. Note that several positive associations are shared between PBC and rheumatoid arthritis (RA).

Gene	PBC	RA
HLA
DR8	+	−
DQB1	+	+
DRB1	+	−
DQA1	+	−
DQA2	+	−
Non-HLA
STAT4	+	+
SPIB	+	−
IRF5	+	+
IL12A	+	−
IL12RB	+	−
MMEL1	+	+
CXCR5	+	?
NFKB1	+	−
CTLA4	+	+

?: question mark indicates that there are no conclusive data regarding the role of CCXR5 as a risk factor in RA, with some reports providing data in support and other against.