24 bp duplication of CHIT1 gene and determinants of human chitotriosidase activity among participants of EPISONO, a population-based cross-sectional study, São Paulo, Brazil.

ABSTRACT

OBJECTIVES: We investigated whether plasma chitotriosidase activity is related to Obstructive Sleep Apnea (OSA) conditions and is correlated with biochemical variables present in the EPISONO database. This is the first study conducted in an epidemiological and nutritional transition country using subjects from the EPISONO population-based cross-sectional study. DESIGN AND METHODS: Chitotriosidase (CHIT) activity was determined by fluorimetric assay. OSA classification was defined as an apnea-hypopnea index. The correlations were investigated using a multiple regression linear model and statistical criteria, with CHIT as the dependent variable and correlated variables (from the EPISONO database) as independent variables, to access the contribution of each one to the variation in CHIT activity. RESULTS: No significant difference was observed when comparing the mean CHIT activities of different apnea groups. The prevalence of the CHIT1 24-bp duplication from patients with severe apnea was higher than in controls. In a multiple regression linear model, CHIT concentration was positively associated with age, creatine and testosterone. Age was the strongest predictor of CHIT variation, followed by gender, waist circumference and TNFα levels. The whole regression model explained 14% of the CHIT variation. CONCLUSION: Many variables are related to CHIT activity and show evidence of the multifactor and potentially synergistic character of this enzyme. In this study, we found that age, gender, TNFα, Hcy, sleep efficiency and waist circumference were responsible for approximately 14% of CHIT variation. Further studies are needed to elucidate additional parameters that may be related to CHIT activity.