Tribal and geographical variations of lupus in the Sultanate of Oman: a hospital-based study

Tribal differences are demonstrated in the presentation of lupus in Omani Gulf Arabs (OGA) and Omani Arabs of Persian descent (OAP), both groups resident in and indigenous to the Sultanate of Oman. The OAP have a lower risk of joint complications, skin rash, and dsDNA antibodies than OGA (beta coefficient and 95% confidence interval [CI], -35.6, -16.4, and -2.31 and -38.05 to -33.06, -19.49 to -13.3, and -4.1 to -0.6, respectively). The OGA have higher levels of IgG isotype APL antibodies than OAP, both anticardiolipin (ACA) (t = 1.75, P = 1.04) and anti-beta(2)glycoprotein I (proportional tobeta(2)GPI) (t = 3.64, P = 0.004) antibodies, while OAP have higher levels of ACAs, IgM isotype (t = 2.86, P = 0.0024), than OGA. Antiphospholipid (APL) antibodies associate differently with clinical symptoms, both within OAP and between OAP and OGA. Patients from Dakiliyah have a higher risk of joint disease than those from Muscat (relative risk ratio 5.0, 95% CI 1.3 18.3). Differences in symptomatology suggest variations in genetic linkages to human systemic lupus erythematosus.