Lack of Association of TYK2 Gene Polymorphisms in Chinese Patients with Systemic Lupus Erythematosus

To the Editor: We read with interest the study of Hellquist, et al 1 showing tyrosine kinase 2 ( TYK2 ) is associated with systemic lupus erythematosus (SLE). Similar results have been reported in different Caucasian populations2,3,4, but not in a recently published Japanese study5. Interestingly, we also found TYK2 polymorphisms were not associated with SLE in Hong Kong Chinese, although subphenotype analysis revealed it may be associated with the development of photosensitivity and discoid rash. Our study was approved by the Institutional Review Board of the University of Hong Kong/Hospital Authority Hong Kong West Cluster. The study included 669 patients with SLE and 2538 controls, as reported6,7. Genotyping with the Illumina 610-Quad Human Beadchip (Illumina, San Diego, CA, USA) from 612 patients and 2193 healthy controls included 9 single-nucleotide polymorphisms (SNP) within 10 kilobases spanning TYK2 . Additional genotyping by direct sequencing on 150 patients and 345 healthy controls was performed for rs12720270, rs2304356, and rs2304255, which were not included … Address correspondence to Dr. Lau; E-mail: lauylung{at}hkucc.hku.hk