The Genetics of Respiratory Failure in Bronchiolitis

Bronchiolitis is a potentially severe infection of the airway in infants and children, and among the most frequent diagnoses leading to pediatric intensive care unit admission in infants. This acute infection is caused by an array of viruses, but respiratory syncytial virus (RSV) is the most frequently implicated. The majority of infants hospitalized with bronchiolitis are previously healthy, and half of infants intubated and mechanically ventilated for respiratory failure due to RSV bronchiolitis have no previously identified risk factors. It is likely, therefore, that other factors, particularly genetic heterogeneity of the host, contribute to disease severity. However, no previous study has investigated the association of genetic variants with respiratory failure in children with bronchiolitis. Several categories of candidate genes have emerged as potentially important in the pathogenesis of the disease. Specifically, genetic polymorphisms of surfactants, pattern recognition receptors, receptor adhesion molecules, and cytokines have been examined. The aim is to evaluate these polymorphisms to determine their association with respiratory failure in a cohort of more severely ill children with bronchiolitis.

Children hospitalized with bronchiolitis

• Cases
  Children hospitalized in the ICU with bronchiolitis
• Controls
  Children hospitalized in the general ward with bronchiolitis

Inclusion Criteria, cases:

• admission to the ICU with a primary diagnosis of bronchiolitis
• endotracheally intubated and mechanically ventilated with respiratory failure due to bronchiolitis
• age less than 2 years

Exclusion Criteria, cases:

• pre-existing chronic disease including:

  1. bronchopulmonary dysplasia
  2. congenital heart disease
  3. immune deficiency
• requiring an additional venopuncture for blood collection for genotyping

Inclusion Criteria, controls:

• admission to the hospital with a primary diagnosis of bronchiolitis
• age less than 2 years

Exclusion Criteria, controls:

• pre-existing chronic disease including:

  1. bronchopulmonary dysplasia
  2. congenital heart disease
  3. immune deficiency
• requiring an additional venopuncture for blood collection for genotyping
• requiring non-invasive positive pressure ventilation or high flow nasal cannula
• requiring intubation and mechanical ventilation during the hospitalization