Abstract
OBJECTIVES: Nonsegmental vitiligo (NSV) is frequently associated with thyroid autoimmunity (TAI), however, the immunopathogenic mechanisms of such association remain to be investigated. The aims of this work were to estimate the frequency of TAI and to describe the genetic polymorphism in the human leukocyte antigen (HLA)-DRB1 and -DQB1 loci in TAI susceptibility among patients with NSV. PATIENTS AND METHODS: In this cross-sectional study, screening for TAI was performed in 97 Moroccan patients with NSV by measuring antibodies against thyroid peroxidase (TPOAb) and thyroglobulin (TGAb). HLA-DRB1 and -DQB1 were determined with single specific primer-polymerase chain reaction (PCR-SSP) typing methods. RESULTS: TAI was diagnosed in 20 patients with NSV (20.6%). The phenotypic frequency of DQB1*05 (OR = 5.04; P = 0.006; pc = 0.036) was significantly higher in NSV patients with TAI. Genotype DQB1*05/DQB1*06 (OR = 25.33; P = 0.001; pc = 0.003) confer susceptibility to TAI in NSV patients. NSV patients with TAI and early onset vitiligo have an extremely high phenotype frequency of DQB1*05 allele (OR = 14.67; P = 0.001; pc = 0.048) and DQB1*05/DQB1*06 genotype (OR = 26.55; P = 0.01; pc = 0.03). TAI in patients with NSV was (6.2%) associated with onset of clinical thyroid disease based on TSH and free T4. CONCLUSION: Our findings suggest that HLA-DQ polymorphisms influence TAI risk in subjects with NSV, although HLA does not completely explain the co-occurrence of these two diseases.