120 Duplication in CHIT1 gene and the risk for Aspergillus lung disease in CF patients

Abstract

Summary. Background: Aspergillus often persists in the respiratory tract of patients with Cys-tic Fibrosis (CF) and may cause allergic broncho-pulmonary aspergillosis (ABPA). Chitinasesare enzymes that digest the chitin polymer. Plants use chitinase as a defense mechanismagainst fungi. Chitotriosidase (CHIT1) is the major chitinase in human airways. Variation in thecoding region with 24-bp duplication allele results in reduced CHIT1 activity. Recently, CHIT1duplication heterozygocity was found in 6/6 patients with severe asthma and fungal sensitiza-tion (SAFS). Aim: Our aim was to evaluate the link between CHIT1 duplication in CF patientsand the predisposition to Allergic broncho-pulmonary mycosis (ABPM) or persistent Aspergilluspositive sputum (APS). Patients and Methods: CHIT1 duplication was assessed in three CFgroups. Group 1: patients who had neither ABPM nor APS in the past (control group). Group2: patients with persistent APS ( 2/year), without ABPA. Group 3: patients with current or pastABPM. Results: Forty patients with CF were included in the analysis, CHIT1 duplication hetero-zygocity was found in 3/6 (50%) of the patients in the ABPM group, 3/12 (25%) in the APSgroup, and 7/22 (31.8%) in the control group (P > 0.05). Eleven patients carried W1282X mu-tation, 90.9% were negative for CHIT1 duplication, five of them were homozygous for W1282X;none of them had CHIT1 duplication or ABPM. Conclusions: CHIT1 duplication is not found inall CF patients with ABPM in contrast to patients with SAFS. These results suggest that CHIT1duplication cannot be the sole explanation for Aspergillus positive sputum in CF patients.Pediatr Pulmonol. 2014; 49:21–27.