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Surfactant Disorders

Healthy lungs contain millions of tiny air sacs (alveoli) which fill with air when we breathe in. When we breathe in, oxygen from the air inside our alveoli travels across the alveolar surface and into the bloodstream. In return, carbon dioxide (a waste gas from our cells) is transported from the bloodstream into the alveoli and is breathed out.  

The surface of the alveoli is covered in a thin liquid layer that contains water and pulmonary surfactant. Surfactant makes it easier for alveoli to stay open so the lungs can work normally. If there is not enough surfactant, the alveoli may collapse and get smaller. This makes it harder for oxygen to get to the body. 

The lungs start making surfactant around the 24th week of pregnancy. They don’t make enough surfactant for the lungs to work normally until 35 weeks. Babies who are born early may need doctors to give the lungs surfactant to help their breathing because their lungs are not making enough. 

Important proteins help build surfactant and make it work in the right way. Problems with any of these proteins can cause breathing problems and lung injury. Surfactant protein B (SP-B) and C (SP-C) help make up surfactant structure. ABCA3 is a protein that moves surfactant in the cells of the lungs. Thyroid transcription factor (TTF1) is a protein that switches on genes that help with surfactant production and function. 

Problems with surfactant make up about 10% of all chILD.