Evidence for HLA Class II Susceptible and Protective Haplotypes for Osteomyelitis in Pediatric Patients with Sickle Cell Anemia.

Background and Objective: Osteomyelitis (OM) is a common complication and significant cause of morbidity in patients with sickle cell anemia (SCA); however, its mechanisms are poorly understood. In view of their link to inflammatory diseases and autoimmune disorders, we investigated the association of HLA class II alleles and haplotypes with the pathogenesis of OM in Bahraini SCA patients.

Patients and Methods. SCA patients comprised 42 with and 150 patients without OM; HLA-DRB1* and -DQB1* genotyping was done by PCR-SSP. HLA allele frequency was determined by the gene counting method, and haplotype frequency was determined by the maximum-likelihood method.

Results. At the allele level, only DRB1*100101 (0.229 vs. 0.082, Pc = 0.003) was positively associated with OM after applying the Bonferrni correction factor. At the haplotype level, DRB1*070101-DQB1*0201 (Pc = 0.001), and DRB1*100101-DQB1*050101 (Pc = 0.001) were more prevalent among patients, while DRB1*030101-DQB1*0201 (Pc = 0.020) and DRB1*040101-DQB1*0302 (Pc = 0.039) was more prevalent among controls, thereby conferring disease susceptibility or protection to these DRB1*-DQB1* haplotypes, respectively.

Conclusion. These results demonstrate that specific HLA halpotypes influence osteomyelitis risk in SCA, thereby suggesting that specific HLA types may serve as a marker for identifying SCA patients at high risk for osteomyelitis.