Abstract
The genetic and epigenetic architecture of clinical and subclinical hypothyroidism remains unclear. We investigated the impact of long noncoding RNA (LncRNA)-PAX8-AS1 and LAIR-2 genetic variants on the susceptibility to clinical and subclinical hypothyroidism, their influence on LncRNA-PAX8-AS1 and LAIR-2 expression and their potential as hypothyroid biomarkers. Hundred clinical hypothyroid patients, 110 subclinical hypothyroid patients, and 95 healthy controls were enrolled. Gene expression analysis and genotyping were performed by qPCR. LAIR-2 protein, a proinflammatory mediator, was tested by ELISA. Serum LncRNA-PAX8-AS1 was downregulated, whereas LAIR-2 mRNA and protein levels were upregulated in clinical and subclinical hypothyroid patients compared to healthy controls. LncRNA-PAX8-AS1 rs4848320 and rs1110839 were associated with increased risk of clinical hypothyroidism. Interestingly, both SNPs were associated with differential expression of serum LncRNA-PAX8-AS1 among clinical hypothyroid patients. LAIR-2 rs2287828 was associated with elevated risk of both clinical and subclinical hypothyroidism. Harboring the rs2287828 T allele augmented the LAIR-2 mRNA expression among clinical hypothyroid patients, while elevated both LAIR-2 mRNA and protein levels in subclinical hypothyroid patients. The rs4848320-rs1110839-rs2287828 TTT, CTT, and CGT haplotypes were associated with increased hypothyroid risk. Surprisingly, serum LncRNA-PAX8-AS1 and LAIR-2 mRNA expression demonstrated superior diagnostic accuracy for clinical hypothyroidism and turned out as independent predictors in the multivariate analysis. Conclusively, LncRNA-PAX8-AS1 and LAIR-2 genetic variants are novel genetic biomarkers of hypothyroidism that could alter the LncRNA-PAX8-AS1 and LAIR-2 expression. LncRNA-PAX8-AS1 and LAIR-2 expression profiles have the potential as effective diagnostic and prognostic indicators of hypothyroidism.