The goal of the study is to learn more about tests that can assess lung health in children with Down syndrome.

Inclusion Criteria:

• Children aged 3 to 18 years, inclusive, at time of consent
• Diagnosis of Down syndrome/trisomy 21 or mosaicism
• Able to walk
• Had a swallow study (video fluoroscopic swallow study or fiberoptic endoscopic evaluation of swallowing) performed within 5 years of consent date

Exclusion Criteria:

• Pregnant or lactating
• Nonambulatory
• Have a tracheostomy or other known severe glottic or subglottic obstruction that would significantly affect the results of testing
• Have a significant acute respiratory illness, defined as treatment with steroids, antibiotics, or an increase in supplemental oxygen
• have a medical illness that would a)increase the risk the participate would incur by participating in the study, b) interfere with the outcomes of the study, or c) interfere with the performance of study participants
• Have a severe behavioral problem that would interfere with the performance of study procedures

Children aged 3-18 years (inclusive) with a diagnosis of Down syndrome who have had a swallow study in the previous 5 years