Clinical and serological follow-up of 71 patients with anti-mitochondrial type 5 antibodies

Antimitochondrial M5 type antibodies (AMA M5) have been described in patients with antiphospholipid syndrome (APS), thrombocytopenia and autoimmune hemolytic anemia. The aim of this study was to describe the clinical and immunological characteristics of a series of patients with AMA M5. We analyzed 71 patients with AMA M5 seen consecutively at our centres during the last 8 years. The clinical and immunological characteristics of diseases expression were compared with 70 consecutive disease control patients without AMA M5. Compared with the control group, AMA M5 positive patients presented higher prevalence of false positive VDRL test (P < 0.00 1) and thrombocytopenia (P = 0.002) with lower levels of anti-beta 2 glycoprotein I antibodies. In AMA M5 patients (56 female, 15 male) a heterogeneous group of disorders were found. Twenty-seven (38%) patients fulfilled the Sapporo criteria for the classification of the APS. Laboratory criteria were met in 55 (77.5%). and clinical criteria in 31 (43.7%) patients. Six patients initially presented with non-criteria features of APS during follow-up period developed APS. Younger patients with AMA M5 should be carefully observed for the development of APS, even in the absence of serological criteria, while elderly must be screened for monoclonal gammopathy and hematological disorders.