CX3CR1 polymorphisms associated with an increased risk of developmental dysplasia of the hip in human.

Developmental dysplasia of the hip, also termed congenital hip dislocation, is one of the major causes of children disability and early onset osteoarthritis. Previous study has identified a variant of CX3CR1 underlying this disorder in a large family. However, genetic evidence from population was still lacking. Here, we performed a case-control association study by genotyping two SNPs of CX3CR1, rs3732378, and rs3732379, in 689 unrelated hip dislocation patients and 689 normal controls. Genotyping results showed significant difference in genotype distributions of both two polymorphisms (p = 0.003 for rs3732378 and p = 0.017 for rs3732379). The minor allele frequency of rs3732378 was higher in cases (4.79%) than in controls (2.47%), predisposing carriers to hip dislocation with a 2.25-fold risk (OR = 2.25, 95%CI 1.42-3.56) after adjustment for gender. Another SNP, rs3732379, was also significantly associated with an increased risk of hip dislocation (adjusted OR = 1.84, 95%CI 1.19-2.84). Through the population study, we demonstrated that CX3CR1 was candidate for the pathogenesis of the disorder, and identified rs3732378 and rs3732379 as susceptibility loci instead of disease-causing mutations.