Mannose-Binding Lectin Deficiency and Its Impact on Pulmonary Morbidity in Children

A mannose-binding lectin (MBL) deficiency, due to MBL2 gene polymorphisms, is suggested to increase susceptibility to respiratory tract infections, particularly in young children. This study aimed to determine whether a MBL deficiency might be associated with pulmonary morbidity in children with recurrent pulmonary infections of unknown pathogenesis. We performed a retrospective, cross-sectional study on children referred to a tertiary pediatric pulmonary center between 2006 and 2011. We included children with a conclusive MBL2 genotype that exhibited recurrent pulmonary infections without any obvious explanatory findings. Pulmonary morbidity was estimated by lung function, body mass index, antibiotic prescriptions, and the odds ratio of radiological structural lung changes, assessed with chest X-rays or high-resolution computed tomography. One hundred thirteen children were included. No significant differences in lung function (z-scores), body mass index, or the number of annual courses of antibiotics per year could be demonstrated between high- and low-expression MBL2 genotypes. The odds ratio of structural lung changes was not related to the MBL2 genotypes. Pulmonary morbidity was not associated with low-expression MBL2 genotypes in a highly selected, although heterogeneous, group of children with recurrent pulmonary infections of unknown pathogenesis. Thus, most likely, a MBL genotyping cannot be used as a single, explanatory, causative factor for detecting differences in pulmonary morbidity in children.