Ethnic distribution and clinical features of systemic lupus erythematosus in the Sudan

ABSTRACT

Systemic lupus erythematosus [SLE] is a multisystem chronic inflammatory autoimmune disease characterized by periods of remissions and relapses. It is thought to develop when genetically predisposed individuals are exposed to one or more environmental triggers. The ethnically mixed population of the Sudan offers an opportunity to look into the effect of ethnicity on the distribution and systemic expression of the disease. Eighty seven consecutive patients fulfilling the clinical and laboratory criteria for the diagnosis of SLE were prospectively interviewed and examined using a unified protocol in three medical clinics in different parts of Khartoum. Appropriate investigations, including renal biopsies were carried out when indicated. Eighty three of the 87 patients [95.4%] were females [female to male ratio 20.61]. Mean age at diagnosis was 31.89 years [range 21-30]. The disease was most frequently seen in tribes of mixed ethnicity [Afro-Arabs] and least common in pure African tribes. Thus, subjects with Afro-Arab ancestry constituted 94.3% of the sample seen whereas, subjects from Nubian ancestry [descendents from ancient tribes living in central and northern Sudan] were 5.7% of the group and no subjects from the black tribes of Southern and Western Sudan were represented. The disease affected multiple systems as seen elsewhere. Most of the patients [96.6%] were antinuclear antibodies [ANA] positive while [51.1%] were antidouble stranded dioxyribonucleic acid [Anti-dsDNA] positive. The clinical features of SLE in our patients are comparable to what has been studied in the region. However, there was an overwhelming tendency of the disease to affect subjects of mixed ethnicity and less affection of subjects of pure African ancestry. The study is in support of the observation that SLE is rare in Black Africans living in Africa, however, it is not uncommon in subjects with Afro-Arab genetic admixture