Ireland has the worlds highest prevalence of CF, at one in 1353.Although technically a rare disease, CF is ranked as one of the most widespread life-shortening genetic diseases. It is most common among nations in the Western world. An exception is Finland, where only one in 80 people carries a CF mutation. The World Health Organization states, "In the European Union, one in 2000–3000 newborns is found to be affected by CF". In the United States, one in 3,500 children is born with CF. In 1997, about one in 3,300 white children in the United States was born with CF. In contrast, only one in 15,000 African American children have it, and in Asian Americans, the rate was even lower at one in 32,000.Cystic fibrosis is diagnosed equally in males and females. For reasons that remain unclear, data have shown that males tend to have a longer life expectancy than females, though recent studies suggest this gender gap may no longer exist, perhaps due to improvements in health care facilities. A recent study from Ireland identified a link between the female hormone estrogen and worse outcomes in CF.The distribution of CF alleles varies among populations. The frequency of ΔF508 carriers has been estimated at one in 200 in northern Sweden, one in 143 in Lithuanians, and one in 38 in Denmark. No ΔF508 carriers were found among 171 Finns and 151 Saami people. ΔF508 does occur in Finland, but it is a minority allele there.
CF develops when neither allele can produce a functional CFTR protein. Thus, CF is considered an autosomal recessive disease.The CFTR gene, found at the q31.2 locus of chromosome 7, is 230,000 base pairs long, and creates a protein that is 1,480 amino acids long. More specifically, the location is between base pair 117,120,016 and 117,308,718 on the long arm of chromosome 7, region 3, band 1, subband 2, represented as 7q31.2. Structurally, the CFTR is a type of gene known as an ABC gene. The product of this gene (the CFTR protein) is a chloride ion channel important in creating sweat, digestive juices, and mucus. This protein possesses two ATP-hydrolyzing domains, which allows the protein to use energy in the form of ATP. It also contains two domains comprising six alpha helices apiece, which allow the protein to cross the cell membrane. A regulatory binding site on the protein allows activation by phosphorylation, mainly by cAMP-dependent protein kinase. The carboxyl terminal of the protein is anchored to the cytoskeleton by a PDZ domain interaction. The majority of CFTR in the lungs passages is produced by rare ion-transporting cells that regulate mucus properties.In addition, the evidence is increasing that genetic modifiers besides CFTR modulate the frequency and severity of the disease. One example is mannan-binding lectin, which is involved in innate immunity by facilitating phagocytosis of microorganisms.