Shared susceptibilities between knee osteoarthritis and hip osteoarthritis.

Abstract

Dear Editor, Recently, we have read the publication “Association of IL-17A-197G/A and IL-17F-7488T/C polymorphisms and osteoarthritis (OA) susceptibility: A meta-analysis”1 with great interest. However, the meta-analyses involved in this article only addressed the risk of knee osteoarthritis (KOA). As is known, the prevalence of hip and KOA varies by ethnicity. Asian populations show a higher prevalence for KOA and a lower prevalence for hip OA (HOA), notably in Chinese and Japanese compared with populations of European descent.2 These differences in the prevalence of KOA and HOA may also indicate genetic heterogeneity in ethnicity and predilection sites (knee or hip). Given that the interaction between genetic and environmental factors in OA is still not well understood and only a small fraction of the genetic determinants has been confirmed with biological explanations, it is necessary to elucidate the potential shared susceptibilities between KOA and HOA. So far, there have been only four research reports on the interleukin (IL)17F gene and OA susceptibility in Han Chinese populations,3-6 except the report from Gao et al1 However, these four articles are all about KOA, not HOA. Moreover, two articles reported a significant association between rs763780 and KOA risk,3, 5 while the other two articles did not identify the association of rs763780 with KOA risk.4, 6 Different studies on KOA susceptibility in the same population have yielded conflicting results, which makes it even more necessary to conduct a deeper systematic genetic association analyses in Han Chinese populations and even other populations. Moreover, these four articles simply examined the association of the single nucleotide polymorphism (SNP) rs763780 with KOA risk, not including the common SNPs of the entire IL17F gene. It is unknown whether the SNP of rs763780 may coexist in linkage disequilibrium with other ungenotyped SNPs or variants to contribute to the risk of OA. What is more, there has been no study of the association of the IL17F gene with HOA risk in Han Chinese populations to date, so additional studies are particularly necessary to systemically evaluate the relationship between IL17F gene and HOA in different populations worldwide including Han Chinese populations. None.