Thyroid-associated ophthalmopathy in black South Africans with Graves' disease - Relationship to serum antibodies reactive against eye muscle and orbital connective tissue autoantigens

The prevalence of hyperthyroidism owing to Graves' disease is increasing am ong urban black South Africans. Thyroid-associated ophthalmopathy is often observed in this context, but its pathogenesis remains unclear. No close re lationship has been noted between antiflavoprotein (Fp) antibodies or thyro tropin receptor antibodies and ocular involvement in black patients. We mea sured serum antibodies against eye muscle and orbital connective tissue ant igens in black patients with Craves' disease, correlating them with eye sig ns. Of 11 patients with clinical ophthalmopathy, 2 (18%) had antibodies aga inst collagen type XIII, 3 (27%) against flavine adenine dinucleotide (FAD) , 1 (9%) against Fp, and 4 (35%) against G2s, Antibody prevalences in eight patients without clinical ophthalmopathy were 12.5% for collagen XIII, 12. 5% for FAD, 25% for Fp and 0% for G2s, These differences were not statistic ally significant. None of the individual mean antibody levels were signific antly different between the two subgroups of thyrotoxic patients. Serum ant ibody levels were negative in 10 black South African controls. In summary, eye muscle and orbital connective tissue antibodies were found in small pro portions of patients with Graves' disease with no close relationship of any antibody to eye signs. Thus, a substantial proportion of black South Afric ans with overt clinical ophthalmopathy remains in whom currently availabe s erologic tests are unhelpful for screening and laboratory confirmation.