Rheumatology Department, Wrightington Hospital, Hall Lane, Appley Bridge, Wigan, Lancashire WN6 9EP, UK
SIR, I am interested to see that Vaidya and co-workers have shown different genetic associations in rheumatoid subjects with and without autoimmune endocrine disease [1].
In studies made in 1986 of HLA haplotype sharing by rheumatoid arthritis sibling pairs, we demonstrated different HLA haplotype sharing by subjects with and without family histories of autoimmune thyroid disease [2]. We predicted then that rheumatoid disease was genetically heterogeneous [2, 3] and the findings of Vaidya and colleagues are in keeping with this prediction. This will be important for future studies of the genetic basis of rheumatoid disease as it is likely to be more productive to look for genetic associations in well-defined clinical and genetic subgroups than to look for evidence of associations in clinically less well defined, albeit larger populations.
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