Role of Polymorphism in HLA DQ-alpha and -beta Chain Loci in the Pathophysiology of Autoimmune Thyroid Disease in Children with and without Turner Syndrome

ABSTRACT

PURPOSE: About 10% of girls with Turner syndrome may have autoimmune thyroid disease(AIT), but the disease's pathophysiology has not yet been elucidated. Accordingly, this study was performed to observe whether the pathogenesis of AIT in children with Turner syndrome and without Turner syndrome correlate with special loci of DQ and chain in HLA. METHODS: Blood samples were drawn from children with and without Turner syndrome. Thyroid antibodies(anti-thyroglobulin and anti-microsomal antibody) were measured from the samples to determine AIT. DNAs were extracted with the DNA extraction kit and processed in PCR reaction for amplification of exon 2 region of HLA-DQA1 and -DQB1, and then eluted again. The eluted PCR products were sequenced directly with an automatic sequencer. The sequences were compared with those of normal control. RESULTS: There was a signficant increase in frequencies of HLA DQA1*0301(P<0.05) and HLA DQB1*0601 but without statistical significance(P=0.06) in normal children with AIT, compared with those in control group. There was signficantly but slightly increased frequency of HLA DQA1*0104, 0105 and DQB1*0202 in the group of children with Turner syndrome who had AIT than in control group. The frequency of the marker chromosome(45,X/46,XX+mar) increased in children with Turner syndrome who had AIT, compared with these in children with Turner syndrome who did not have AIT. Children with Turner syndrome who had spontaneous puberty had higher a incidence rate of AIT than those who did not have spontaneous puberty(P<0.01). CONCLUSION: The results suggest that HLA DQA1*0301 and HLA DQB1*0601 play a role in the pathogenesis of AIT in children without Turner syndrome, but not in children with Turner syndrome. Additionally, there seem to be other factors participating in the pathogenesis of AIT in children with Turner syndrome, such as chromosomal karyotype and spontaneous puberty. Therefore, the factors participitating in the pathogenesis of AIT in children with Turner syndrome remain to be elucidated with further study.