ABSTRACT
AIM:To explore the association between single nucleotide polymorphism in exon 33 (E33SNP) of thyroglobulin gene and Graves ’ disease ( GD) relapse after antithyroid drug ( ATD) withdrawal .METHODS:The healthy controls (232 cases) and GD patients with discontinued treatment (243 cases) were selected.According to the time of re-lapse, the GD patients were divided into A, B and C subgroups.The A group contained 77 cases of relapse within 1 year, B group contained 86 cases of relapse 1~2 years after treatment and C group contained 80 cases without recurrence within 2 years.The genotypes of E33SNP were identified by RT-PCR.The genotype ratio of thyroglobulin between control group and observation group was comparatively analyzed , and the levels of thyroid-stimulating hormone ( TSH) , free triiodothyro-nine (FT3), free thyroxine (FT4) and thyrotropin receptor antibody (TRAb), ophthalmopathy and goiter size in A , B and C subgroups in different genotype GD patients were investigated .Moreover , cumulative efficiency for patients with different genotypes in the observation group after ATD treatment within 2 years were analyzed .RESULTS:The genotype of E33SNP between observation group and control group had no significant difference , but a significant difference between A , B and C subgroups was observed (P<0.05).The levels of TSH, FT3 and FT4, and goiter size of the patients with different geno-types had no significant difference , while the TRAb levels and ophthalmopathy presented a significant difference ( P <0.05).In addition, the cumulative efficiency within 2 years for GD patients with E33SNP T/T, E33SNP T/C and E33SNP C/C genotypes was 61.8%, 42.6% and 21.3%, respectively, all with significant differences (P<0.05).CONCLU-SION:The GD patients with E33SNP C/C genotype have significantly higher TRAb level and ophthalmopathy rate than those in the patients with E33SNP C/T and E33SNP C/C genotypes, and are more likely to relapse after ATD treatment . The GD patients with E33SNP T/T genotype show a lower recurrence rate .Therefore, combination treatment or other treat-ment modalities may be more reasonable for the GD patients with E 33SNP C/C genotype.