A population-based characterization study of anti-mitochondrial M2 antibodies and its consistency with anti-mitochondrial antibodies.

Abstract

This study aims to estimate the prevalence of anti-mitochondrial antibody subtype M2 (AMA-M2) and assess its consistency with AMA in a general population. A total of 8954 volunteers were included to screen AMA-M2 using enzyme-linked immunosorbent assay. Sera with AMA-M2>50 RU/mL were further tested for AMA using an indirect immunofluorescence assay. The population frequency of AMA-M2 positivity was 9.67%, of which 48.04% were males and 51.96% were females. The AMA-M2 positivity in males had a peak and valley value of 7.81% and 16.88% in those aged 40 to 49 and ≥70years, respectively, whereas it showed a balanced age distribution in females. Transferrin and immunoglobulin M were the risk factors for AMA-M2 positivity and exercise was the only protective factor. Of 155 cases with AMA-M2>50 RU/mL, 25 cases were AMA-positive, with a female-to-male ratio of 5.25:1. Only 2 people, with very high AMA-M2 of 760 and >800 RU/mL, met the diagnostic criteria of primary biliary cholangitis (PBC), making the prevalence of PBC 223.36 per million in southern China. We found that AMA-M2 has a low coincidence rate with AMA in the general population. Anew decision-making point for AMA-M2 is needed to improve consistency with AMA and diagnostic accuracy.