1. ¹Department of Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
2. ²Center for Rheumatology Research, Landspitali, Reykjavik, Iceland
3. ³Department of Medicine, Rheumatology Unit, Karolinska Institutet/Karolinska University Hospital, Solna, Sweden
4. ⁴Department of Rheumatology, Lund University Hospital, Lund, Sweden
5. ⁵Department of Immunology and Rheumatology, Instituto Nacional de Ciencias Médicas y Nutrición 'Salvador Zubirán', Mexico City, Mexico
6. ⁶Servicio de Reumatología, Hospital Interzonal General de Agudos 'Dr Oscar Alende', Mar del Plata, Argentina
7. ⁷Servicio de Reumatología de la UHMI 1, Hospital Nacional de Clínicas, Universidad Nacional de Córdoba, Córdoba, Argentina
8. ⁸Hospital General de Agudos Dr Juán A Fernandez, Buenos Aires, Argentina
9. ⁹Facultad de Ciencias Medicas, Universidad Nacional de Rosario y Hospital Provincial del Centenario, Rosario, Argentina
10. ¹⁰Servicio de Reumatología, Hospital Privado, Centro Medico de Córdoba, Córdoba, Argentina
11. ¹¹Sección de Reumatología, Hospital José M Cullen, Santa Fe, Argentina
12. ¹²Hospital San Martín, Paraná, Entre Ríos, Argentina
13. ¹³Departamento de Inmunología, Instituto de Investigaciones Médicas 'Alfredo Lanari', Buenos Aires, Argentina
14. ¹⁴Sección 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
15. ¹⁵Servicio de Reumatología, Hospital Provincial de Rosario, Rosario, Argentina
16. ¹⁶Hospital de Niños Dr Orlando Alassia, Santa Fe, Argentina
17. ¹⁷Servicio de Reumatología Hospital Escuela Eva Perón, Granadero Baigorria, Rosario, Argentina
18. ¹⁸Servicio de Reumatología, Hospital Interzonal General de Agudos General San Martín, La Plata, Argentina
19. ¹⁹Centro de Educación Médica e Investigaciones Clínicas (CEMIC), Buenos Aires, Argentina
20. ²⁰Institute of Laboratory Medicine, Lund University, Lund, Sweden
21. ²¹Sanatorio Parque, Rosario, Argentina

Correspondence: Dr ME Alarcón-Riquelme, Department of Genetics and Pathology, Rudbeck Laboratory, Dag Hammarskjölds väg 20, 751 85 Uppsala, Sweden. E-mail: marta.alarcon@genpat.uu.se

²²Dr Pons-Estel is the coordinator of the Argentinean Collaborative group. All members are found in the appendix at the end.

Received 15 September 2006; Revised 26 October 2006; Accepted 27 October 2006; Published online 30 November 2006.

Abstract

PDCD1, an immunoreceptor involved in peripheral tolerance has previously been shown to be genetically associated with systemic lupus erythematosus (SLE). PDCD1 has two ligands whose genes are located in close proximity on chromosome 9p24. Our attention was drawn to these ligands after finding suggestive linkage to a marker (gata62f03, Z=2.27) located close to their genes in a genome scan of Icelandic families multiplex for SLE. Here, we analyse Swedish trios (N=149) for 23 single nucleotide polymorphisms (SNPs) within the genes of the PDCD1 ligands. Initially, indication of association to eight SNPs was observed, and these SNPs were therefore also analysed in Mexican trios (N=90), as well as independent sets of patients and controls from Sweden (152 patients, 448 controls) and Argentina (288 patients, 288 controls). We do not find support for genetic association to SLE. This is the first genetic study of SLE and the PDCD1 ligands and the lack of association in several cohorts implies that these genes are not major risk factors for SLE.