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

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.