High prevalence of serum apolipoprotein E4 isoprotein in rheumatoid arthritis patients with amyloidosis

Objective. To determine whether serum Apolipoprotein E (Apo E) type 4 isoprotein is a risk factor for the development of amyloidosis in patients with rheumatoid arthritis (RA). Methods. Using isoelectric focusing, we studied Apo E phenotype expression and the corresponding allele frequencies (epsilon 2, epsilon 3, and epsilon 4) in 35 patients with RA and amyloidosis, 65 patients with RA and without amyloidosis, and 63 healthy controls. Results. The Apo E3/4 phenotype was significantly more common in the group with amyloidosis (31.4%) than in the patients without amyloidosis (12.3%; P < 0.05) or in healthy controls (12.7%; P < 0.05). The frequency of the epsilon 4 allele was significantly greater in the group with amyloidosis (0.16) than in the patients without amyloidosis (0.07; P < 0.05) or in healthy controls (0.07; P < 0.05). Conclusion. The presence of Apo E4 isoprotein may be a risk factor for the development of amyloidosis in patients with RA.