FC-GAMMA-RIIA AND FC-GAMMA-RIIIB POLYMORPHISMS IN MYASTHENIA-GRAVIS

The Fc gamma receptors, Fc gamma RIIA and Fc gamma RIIIB contain polym orphisms with different capacity for IgG binding and phagocytosis. Thi rty myasthenia gravis (MG) patients and 49 healthy controls were genot yped for the Fc gamma RIIA and Fc gamma RIIIB polymorphisms using poly merase chain reaction. The frequency of the Fc gamma RIIA-H/H genotype was increased in thymoma MG patients compared to other MG patients (P = 0.05) and controls (P = 0.02). The distribution of Fc gamma RIIIB a lleles in MG patients did not differ from the controls, but MG patient s with the NA1/NA1 genotype had the most severe MG (P = 0.01). Levels of AChR-antibodies and frequency of titin or ryanodine receptor antibo dies were not associated with the Fc gamma RIIA or Fc gamma RIIIB geno types. The results suggest different pathogenetic mechanisms in parane oplastic and non-paraneoplastic autoimmune MG. (C) 1998 Elsevier Scien ce B.V.