1. ¹Rowe Program in Human Genetics, Departments of Biological Chemistry and Medicine, University of California Davis, Davis, CA, USA
2. ²Rowe Program in Human Genetics, Department of Public Health Sciences, University of California, Davis, CA, USA
3. ³Servicio de Reumatología, Hospital Interzonal General de Agudos 'Dr Oscar Alende', Mar del Plata, Argentina
4. ⁴Obras Sociales del Hermano Pedro, Antigua, Guatemala
5. ⁵Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
6. ⁶Servicio de Reumatología de la UHMI 1, Hospital Nacional de Clínicas, Universidad Nacional de Córdoba, Córdoba, Argentina
7. ⁷Hospital General de Agudos Dr Juán A Fernandez, Buenos Aires, Argentina
8. ⁸Facultad de Ciencias Medicas, Universidad Nacional de Rosario y Hospital Provincial del Centenario, Rosario, Argentina
9. ⁹Servicio de Reumatología, Hospital Privado, Centro Medico de Córdoba, Córdoba, Argentina
10. ¹⁰Hospital José M Cullen, Santa Fe, Argentina
11. ¹¹Hospital San Martín, Paraná, Entre Ríos, Argentina
12. ¹²Departamento de Inmunología, Instituto de Investigaciones Médicas 'Alfredo Lanari', Buenos Aires, Argentina
13. ¹³Sección Reumatología, Servicio de Clínica Médica, Hospital Italiano de Buenos Aires y Fundación Dr Pedro M Catoggio para el Progreso de la Reumatología, Buenos Aires, Argentina
14. ¹⁴Servicio de Reumatología, Hospital Provincial de Rosario, Rosario, Argentina
15. ¹⁵Servicio de Reumatología Hospital Escuela Eva Perón. Granadero Baigorria, Rosario, Argentina
16. ¹⁶Servicio de Reumatología, Hospital Interzonal General de Agudos General San Martín, La Plata, Argentina
17. ¹⁷Centro de Educación Médica e Investigaciones Clínicas (CEMIC), Buenos Aires, Argentina
18. ¹⁸Department of Clinical Immunology and Microbiology, Lund University Hospital, Lund, Sweden
19. ¹⁹Merck Serono Inc., Chemin des Mines, Geneva, Switzerland
20. ²⁰Hospital de Niños Dr. Orlando Alassia, Santa Fe, Argentina
21. ²¹Sanatorio Parque, Rosario, Argentina
22. ²²Department of Genetics and Pathology, Rudbeck Laboratory, University of Uppsala, Uppsala, Sweden

Correspondence: Dr ME Alarcon-Riquelme, Department of Genetics and Pathology, Rudbeck Laboratory, University of Uppsala, Uppsala, Sweden. E-mail: marta.alarcon@genpat.uu.se

Received 24 January 2008; Revised 5 March 2008; Accepted 5 March 2008; Published online 10 April 2008.

Abstract

Previous studies have demonstrated that in admixed populations, West African ancestry is associated with an increased prevalence of systemic lupus erythematosus (SLE). In the current study, the effect of Amerindian ancestry in SLE was examined in an admixed population in Argentina. The Argentine population is predominantly European with approximately 20% Amerindian admixture, and a very small (<2% ) contribution from West Africa. The results indicate that Amerindian admixture in this population is associated with a substantial increase in SLE susceptibility risk (Odds Ratio=7.94, P=0.00006). This difference was not due to known demographic factors, including site of collection, age and gender. In addition, there were trends towards significance for Amerindian ancestry influencing renal disease, age of onset and anti-SSA antibodies. These studies suggest that populations with Amerindian admixture, like those with West African admixture, should be considered in future studies to identify additional allelic variants that predispose to SLE.