Cystic fibrosis (CF), also known as mucoviscidosis and popularly called "salty kiss disease", is a genetic disease that affects the respiratory, digestive, and reproductive systems, involving the abnormal production of thick mucus in the lungs, which can lead to fatal lung infections. The disease can also result in obstructions of the pancreas, making digestion difficult.
 
These manifestations are caused by abnormalities in the cystic fibrosis transmembrane receptor (CFTR), present in the epithelial cells of the pulmonary mucosa, which promotes increased resorption of sodium and water and dehydrates the pulmonary secretions, rendering them excessively viscous. This drying of the mucus obstructs the airways, facilitating the development of bacterial infections and an intense inflammatory response.

The affected individual has two deficient genes, one of maternal origin and the other of paternal origin. When parents of these genes conceive a child, there is a 25% chance of transmitting the disease to the child, a 50% chance of the child inheriting the cystic fibrosis gene, and a 25% chance that the child will not inherit the gene.