Using an active cohort of children in whom Airway and gastrointestinal endoscopy will be performed, investigators will conduct a chart review to obtain relevant clinical data and the investigators will use an aliquot of airway sample obtained during the clinically indicated bronchoscopy for microbiome analysis. A case-control study design will be used to study whether subjects with CC with GER have a distinct lung microbiome and increased inflammation as compared with subjects with CC without GER and to determine whether the microbiome and degree of inflammation is related to the type of GER (acidic versus nonacidic).

Inclusion Criteria:

• Children (Age 0 - 24 years) referred to the NYU Pediatric AeroDigestive Center to evaluate for CC (>4weeks).

Exclusion Criteria:

• Antibiotic or steroids (inhaled or systemic) use within the prior one-week. Rationale: Antibacterial drugs and immune-modulators are confounders that may impact the microbiome and inflammation. While longer period free of Antibacterial drugs and immune-modulators would be desired, it would be unethical and it is not the usual standard of care to withdraw treatment for longer periods of time.
• Interstitial Lung Disease or pneumonia on X-ray
• Cystic fibrosis
• Primary ciliary dyskinesia
• Immunodeficiency syndromes
• Major airway abnormalities
• Proton pump inhibitor/H2-receptor antagonist therapy within the prior 2 weeks

Children (Age 0 - 24 years) referred to the NYU Pediatric AeroDigestive Center to evaluate for CC (>4weeks).