Association of insulin-like growth factor-1 receptor polymorphism and insulin-like growth factor-1 plasma level with chronic immune thrombocytopenia in Chinese population

Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by isolated low platelet count and suppression of megakaryocyte development. Abnormalities of cell-mediated immunity have drawn more and more attention in the pathologic process of ITP. Insulin-like growth factor-1(IGF-1) plays an important role in the regulation of immune response and inflammation, which takes place in innate and acquired immunity. A series of studies had demonstrated IGF-1/IGF-1R pathway was involved in several autoimmune disorders. Thus, we speculated that the IGF-1R rs2229765 polymorphism might be associated with genetic susceptibility to ITP in a Chinese Han population. We compared distributions of rs2229765 polymorphism in 197 patients with chronic ITP and 262 normal controls by polymerase chain reaction and direct sequencing. We also investigated IGF-1 plasma level in normal controls and ITP patients associated with gender, age, genotype, and severity by enzyme-linked immunosorbent assay (ELISA). Both A allele and AA genotype distributions revealed statistical difference in male between childhood ITP and gender-matched controls (p < 0.05). However, neither the allele nor genotype frequencies reached significant differences among patients with chronic ITP patients, adult ITP group, female in childhood ITP group and normal controls (p > 0.05). The IGF-1 plasma level in ITP patients was significantly decreased compared with the controls (p < 0.05). In addition, we observed that the IGF-1 concentration of severe group was evidently lower than non-severe group (p < 0.05). However, when ITP patients were respectively stratified by gender, age, and genotype, no significant differences were observed. These results suggest IGF-1R rs2229765 polymorphism may have no relationship with chronic ITP in a Chinese population, but it confirmed at least that IGF-1R rs2229765 polymorphism can be used as an independent predictor for the male in childhood ITP. Abnormal IGF-1 plasma level has contributed to the pathogenesis of chronic ITP patients. IGF-1 plasma level may be used to access the severity of disease, but it has no relationship with IGF-1R rs2229765 polymorphism. These results suggest IGF-1R rs2229765 polymorphism may have no relationship with chronic ITP in a Chinese population, but it confirmed at least that IGF-1R rs2229765 polymorphism can be used as an independent predictor for the male in childhood ITP. Abnormal IGF-1 plasma level has contributed to the pathogenesis of chronic ITP patients. IGF-1 plasma level may be used to access the severity of disease, but it has no relationship with IGF-1R rs2229765 polymorphism.