Interleukin-1 Receptor Antagonist Gene Polymorphisms in Egyptian Children and Adolescents With Primary Immune Thrombocytopenia: Association With Disease Susceptibility, Response to Therapy, and Outcome

Immune thrombocytopenia (ITP) is one of the most common hematologic disorders with poorly predictable clinical course and outcome. We studied the distribution of interleukin 1 receptor antagonist (IL-1Ra) gene polymorphism (intron-2) among children and adolescents with ITP and correlated IL-1Ra gene polymorphism to disease susceptibility, response to therapy, and outcome. Sixty children with ITP (mean age: 9.2 & PLUSMN;4.5 y) and 100 healthy controls (mean age: 8.83 & PLUSMN;4.05 y) were enrolled. The frequencies of the allele A2 and genotype A1A2 were significantly higher in patients compared with controls (P<0.0001, P=0.0008, respectively). Allele A2 conferred 3.1 times increased relative risk for disease development. Allele A2 and genotypes A1A2 and A2A2 were significantly more frequent among remitted patients (P=0.028 and 0.024, respectively). There was no significant difference between different genotypes and alleles regarding bleeding score (P>0.05). Patients with polymorphic allele A2 (A1A2/A2A2) showed significantly better response to steroids than those with homozygous wild allele A1 (P=0.028). IL-1Ra polymorphism might contribute to the susceptibility to ITP in Egyptian children. The presence of A2 polymorphic allele of IL-1Ra gene was found to be associated with better disease outcome and response to steroids than those with homozygous wild allele.