Association of serum chitotriosidase enzyme levels with 24-base pair duplication variant and autoimmune thyroid disease.

Abstract

Emerging research increasingly highlights the role of chitotriosidase (CHIT1) in mediating inflammatory cascades and autoimmune dysfunction. This study sought to evaluate the association between serum chitotriosidase levels, the 24-base-pair duplication (24-bp dup) variant in exon 10 of the CHIT1 gene, and the two main subtypes of autoimmune thyroid disease (AITD). The study cohort comprised 45 treatment-naive AITD patients (categorized into Graves disease and Hashimoto s thyroiditis subgroups) alongside 45 healthy euthyroid control subjects. Clinical evaluation, thyroid imaging, and complete hormone profiling (TSH, FT3, FT4), alongside serological biomarkers thyroid peroxidase antibodies (TPO Ab) and thyrotropin receptor antibodies (TRAb) were used to diagnose AITD and its subtypes. Serum CHIT1 concentrations were determined via sandwich enzyme-linked immunosorbent assay (ELISA), while the CHIT1 gene was assessed for the 24-base pair duplication (24-bp dup) polymorphism using polymerase chain reaction (PCR). Serum CHIT1 concentrations were significantly elevated in the AITD group compared to controls (p < 0.001), with significant elevations observed in both Graves (p < 0.001) and Hashimoto s (p = 0.015) subtypes. However, no significant difference was observed in CHIT1 concentration between the two AITD subtypes (p = 0.994). Participants heterozygous for the CHIT1 24-base pair duplication exhibited significantly lower serum CHIT1 concentrations than the wild-type homozygotes across all the study population (p < 0.001). In conclusion, serum chitotriosidase levels are significantly associated with both autoimmune thyroid disease and the allelic distribution of the CHIT1 exon 10 24-bp dup variant. It should be emphasized that prospective studies with larger cohorts, expanded genotyping studies and appropriate diagnostic performance analyses are needed to establish clinical applicability.