Heterozygous C2 deficiency associated with angioedema, myasthenia gravis, and systemic lupus erythematosus

SUMMARY We describe a patient with myasthenia gravis, systemic lupus erythematosus, and angioedema associated with heterozygous complement factor 2 (C2) deficiency. The significance of this association is controversial, though the association of C2 deficiency with certain histocompatibility antigens suggests possible linkage to immune response genes. To our knowledge this is the first report of heterozygous C2 deficiency in association with this combination of 'autoimmune ' disorders, and we discuss the aetiological implications. The coexistence of myasthenia gravis and systemic lupus erythematosus (SLE) is well recognised, l-5 though the association of these two conditions with angioedema has only once previously been reported.5 Homozygous and, less commonly, hetero-zygous deficiency of complement factor 2 (C2) is also recognised in association with SLE68 but has not previously been described in association with myasthenia gravis. We report on a patient with angioedema, myasthenia gravis, and SLE who had heterozygous C2 deficiency. Case history A 36 year old Caucasian woman known to have myasthenia gravis was admitted to hospital with a one year history of intermittent polyarthritis in-volving the hands, knees, and ankles, Raynaud's phenomenon, and urticarial rashes associated with swelling of her lips and tongue. At the age of 16 years she presented with bilateral ptosis, dysarthria, and dysphagia. Myasthenia gravis was confirmed by electromyography, and she re-sponded well to treatment with pyridostigmine