INTRODUCTION: The largest genetic risk to develop rheumatoid arthritis (RA) arises from a group of alleles of the HLA DRB1 locus ('shared epitope', SE). Over 30 non-HLA single nucleotide polymorphisms (SNPs) predisposing to disease have been identified in Caucasians, but they have never been investigated in West/Central Africa. We previously reported a lower prevalence of the SE in RA patients in Cameroon compared to European patients and aimed in the present study to investigate the contribution of Caucasian non-HLA RA SNPs to disease susceptibility in Black Africans. METHODS: RA cases and controls from Cameroon were genotyped for Caucasian RA susceptibility SNPs using Sequenom MassArray technology. Genotype data were also available for 5024 UK cases and 4281 UK controls and for 119 Yoruba individuals in Ibadan, Nigeria (YRI, HapMap). A Caucasian aggregate genetic-risk score (GRS) was calculated as the sum of the weighted risk-allele counts. RESULTS: After genotyping quality control procedures were performed, data on 28 Caucasian non-HLA susceptibility SNPs were available in 43 Cameroonian RA cases and 44 controls. The minor allele frequencies (MAF) were tightly correlated between Cameroonian controls and YRI individuals (correlation coefficient 93.8%, p = 1.7E-13), and they were pooled together. There was no correlation between MAF of UK and African controls; 13 markers differed by more than 20%. The MAF for markers at PTPN22, IL2RA, FCGR2A and IL2/IL21 was below 2% in Africans. The GRS showed a strong association with RA in the UK. However, the GRS did not predict RA in Africans (OR = 0.71, 95% CI 0.29 - 1.74, p = 0.456). Random sampling from the UK cohort showed that this difference in association is unlikely to be explained by small sample size or chance, but is statistically significant with p<0.001. CONCLUSIONS: The MAFs of non-HLA Caucasian RA susceptibility SNPs are different between Caucasians and Africans, and several polymorphisms are barely detectable in West/Central Africa. The genetic risk of developing RA conferred by a set of 28 Caucasian susceptibility SNPs is significantly different between the UK and Africa with p<0.001. Taken together, these observations strengthen the hypothesis that the genetic architecture of RA susceptibility is different in different ethnic backgrounds.
INTRODUCTION: The largest genetic risk to develop rheumatoid arthritis (RA) arises from a group of alleles of the HLA DRB1 locus ('shared epitope', SE). Over 30 non-HLA single nucleotide polymorphisms (SNPs) predisposing to disease have been identified in Caucasians, but they have never been investigated in West/Central Africa. We previously reported a lower prevalence of the SE in RA patients in Cameroon compared to European patients and aimed in the present study to investigate the contribution of Caucasian non-HLA RA SNPs to disease susceptibility in Black Africans. METHODS: RA cases and controls from Cameroon were genotyped for Caucasian RA susceptibility SNPs using Sequenom MassArray technology. Genotype data were also available for 5024 UK cases and 4281 UK controls and for 119 Yoruba individuals in Ibadan, Nigeria (YRI, HapMap). A Caucasian aggregate genetic-risk score (GRS) was calculated as the sum of the weighted risk-allele counts. RESULTS: After genotyping quality control procedures were performed, data on 28 Caucasian non-HLA susceptibility SNPs were available in 43 Cameroonian RA cases and 44 controls. The minor allele frequencies (MAF) were tightly correlated between Cameroonian controls and YRI individuals (correlation coefficient 93.8%, p = 1.7E-13), and they were pooled together. There was no correlation between MAF of UK and African controls; 13 markers differed by more than 20%. The MAF for markers at PTPN22, IL2RA, FCGR2A and IL2/IL21 was below 2% in Africans. The GRS showed a strong association with RA in the UK. However, the GRS did not predict RA in Africans (OR = 0.71, 95% CI 0.29 - 1.74, p = 0.456). Random sampling from the UK cohort showed that this difference in association is unlikely to be explained by small sample size or chance, but is statistically significant with p<0.001. CONCLUSIONS: The MAFs of non-HLA Caucasian RA susceptibility SNPs are different between Caucasians and Africans, and several polymorphisms are barely detectable in West/Central Africa. The genetic risk of developing RA conferred by a set of 28 Caucasian susceptibility SNPs is significantly different between the UK and Africa with p<0.001. Taken together, these observations strengthen the hypothesis that the genetic architecture of RA susceptibility is different in different ethnic backgrounds.
Authors: Eli A Stahl; Soumya Raychaudhuri; Elaine F Remmers; Gang Xie; Stephen Eyre; Brian P Thomson; Yonghong Li; Fina A S Kurreeman; Alexandra Zhernakova; Anne Hinks; Candace Guiducci; Robert Chen; Lars Alfredsson; Christopher I Amos; Kristin G Ardlie; Anne Barton; John Bowes; Elisabeth Brouwer; Noel P Burtt; Joseph J Catanese; Jonathan Coblyn; Marieke J H Coenen; Karen H Costenbader; Lindsey A Criswell; J Bart A Crusius; Jing Cui; Paul I W de Bakker; Philip L De Jager; Bo Ding; Paul Emery; Edward Flynn; Pille Harrison; Lynne J Hocking; Tom W J Huizinga; Daniel L Kastner; Xiayi Ke; Annette T Lee; Xiangdong Liu; Paul Martin; Ann W Morgan; Leonid Padyukov; Marcel D Posthumus; Timothy R D J Radstake; David M Reid; Mark Seielstad; Michael F Seldin; Nancy A Shadick; Sophia Steer; Paul P Tak; Wendy Thomson; Annette H M van der Helm-van Mil; Irene E van der Horst-Bruinsma; C Ellen van der Schoot; Piet L C M van Riel; Michael E Weinblatt; Anthony G Wilson; Gert Jan Wolbink; B Paul Wordsworth; Cisca Wijmenga; Elizabeth W Karlson; Rene E M Toes; Niek de Vries; Ann B Begovich; Jane Worthington; Katherine A Siminovitch; Peter K Gregersen; Lars Klareskog; Robert M Plenge Journal: Nat Genet Date: 2010-05-09 Impact factor: 38.330
Authors: Philip L De Jager; Lori B Chibnik; Jing Cui; Joachim Reischl; Stephan Lehr; K Claire Simon; Cristin Aubin; David Bauer; Jürgen F Heubach; Rupert Sandbrink; Michaela Tyblova; Petra Lelkova; Eva Havrdova; Christoph Pohl; Dana Horakova; Alberto Ascherio; David A Hafler; Elizabeth W Karlson Journal: Lancet Neurol Date: 2009-10-29 Impact factor: 44.182
Authors: Jan Freudenberg; Hye-Soon Lee; Bok-Ghee Han; Hyoung Do Shin; Young Mo Kang; Yoon-Kyoung Sung; Seung-Cheol Shim; Chan-Bum Choi; Annette T Lee; Peter K Gregersen; Sang-Cheol Bae Journal: Arthritis Rheum Date: 2011-04
Authors: Lori B Chibnik; Brendan T Keenan; Jing Cui; Katherine P Liao; Karen H Costenbader; Robert M Plenge; Elizabeth W Karlson Journal: PLoS One Date: 2011-09-12 Impact factor: 3.240
Authors: Vincent A Laufer; Hemant K Tiwari; Richard J Reynolds; Maria I Danila; Jelai Wang; Jeffrey C Edberg; Robert P Kimberly; Leah C Kottyan; John B Harley; Ted R Mikuls; Peter K Gregersen; Devin M Absher; Carl D Langefeld; Donna K Arnett; S Louis Bridges Journal: Hum Mol Genet Date: 2019-03-01 Impact factor: 6.150
Authors: Peter B Olaitan; Victoria Odesina; Samuel Ademola; Solomon O Fadiora; Odunayo M Oluwatosin; Ernst J Reichenberger Journal: BMC Med Ethics Date: 2014-09-02 Impact factor: 2.652
Authors: Matthew Traylor; Charles Curtis; Hamel Patel; Gerome Breen; Sang Hyuck Lee; Xiaohui Xu; Stephen Newhouse; Richard Dobson; Sophia Steer; Andrew P Cope; Hugh S Markus; Cathryn M Lewis; Ian C Scott Journal: Rheumatology (Oxford) Date: 2017-08-01 Impact factor: 7.580