Mannose-binding lectin 2 gene polymorphism and lung damage in primary ciliary dyskinesia

Background: Mannose-binding lectin (MBL) plays an important role in innate immunity and has been reported to be associated with the age-related decline in lung function in cystic fibrosis. Hypothesis: MBL polymorphisms are associated with lung function decline in Primary Ciliary Dyskinesia (PCD). Methods: We performed sputum microbiology, spirometry preand post-administration of salbutamol, ciliary motion analysis, ultrastructural assessment of cilia, ciliogenesis in culture, and chest high resolution computed tomography in children with a clinical history of respiratory tract infections and/or presence of bronchiectasis suggestive of PCD or secondary ciliary dyskinesia (SCD). All subjects were evaluated for single nucleotide polymorphisms in the gene encoding MBL-2. Results: The diagnosis of PCD was established in 45 subjects, while in the remaining 53 the diagnosis was SCD. A significant bronchodilator response was observed only in PCD associated with the MBL2-3 genotype, which is known to be associated with low/undetectable MBL serum levels. Also, bronchiectasis severity was significantly greater in subjects with MBL2-3 in both PCD and SCD. No other association was found between MBL genotypes and clinical findings. Conclusions: MBL plays a relatively minor role as a disease modifier in PCD. A similar finding in SCD supports the likely significance of this result.