Introduction: Antimitochondrial type M5 antibodies (AMA-M5) are among the immunological abnormalities associated with Sneddon syndrome.
Case: A 45 year-old woman, hospitalized for diplopia and with a 20-year history of obstetrical accidents, internuclear ophthalmoplegia and livedo, was diagnosed with Sneddon syndrome associated with primary antiphospholipid syndrome (APS) aggravated by the presence of AMA-M5.
Discussion: AMA-M5 are immunological markers of APS to the same extent as antiphospholipid antibodies. This case demonstrates the interest of screening for AMA-M5 in cases of strong clinical suspicion of APS when the anticoagulant lupus test is normal and no anti-cardiolipin, anti-b2 glycoprotein I or antiprothrombin antibodies are found.