Mira Tafa

When checking the literature, CFTR protein refers to the gene sequence that encodes for the protein of the same name. In fact, the protein itself is referred to as an ABC transporter, due to it being part of the ATP-binding cassette superfamily. 

What makes this protein distinctive from the others; is its functionality as that of a chloride channel. As the channel operates on the basis of ATP and its hydrolysis, the movement of chloride ions is what would also control the water in the epithelial tissues in terms of its section and absorption of the molecules of water. Mutation of this gene, which is located on chromosome 7, result in the emerge of Cystic Fibrosis genetic disease, that is most commonly spread within Caucasian descents. 

 

The most common mutation of the disease is referred to as p. F508del coming as a result of a three base pair deletion. A study conducted on 1989, year at which the gene was discovered, suggested that this mutation was a result of a single event, and such factor made the probably of carrying the mutated gene or exhibiting the disease, higher. Even though Cystic Fibrosis (an autosomal recessive disorder) can be considered as a homogenous disease, there are cases when diagnosed patients did not have a mutation in the CFTR gene at all. The mutations in those other regions might as well called “phenocopies” of the disease. 

 

Nonetheless, the major question of this paper remains on the timing when the disease emerged. Philip Farrell, a professor at University of Wisconsin-Madison was able to conduct a study in Austria including 32 skeletons that were buried at around 350 B.C and were being preserved at the Natural History Museum of the capital. The collected DNA from the corps’ teeth identified 3 individuals having the p. F508del mutation. Such a high ratio, 3 amongst 32 skeletons overall provided scientists with the knowledge that the disorder had been present throughout the population even much earlier than age of those European skeletons. Also, it was thought that all mutation containing the specimens belonged to carriers, as at the time survival rate of CF patients would be pretty close to zero. 

By far, the oldest person to have the p. F508del mutation within his DNA is thought to have lived within France and Portugal, and it is believed that have lived 4.600 - 4.725 years ago. Then the mutation got spread in the region that today belong to the United Kingdom and Ireland. 

 

 

Later on, the mutation started spreading even more as people of the Bronze Age would migrate a lot. However, it is yet unknown if this mutation was beneficial to the carriers. There is a hypothesis suggesting that due to massive migrations there must have been a period where infections and epidermic would be extremely common, and a single copy of the mutated CFTR gene might have been advantageous to combat a possible plague of the time, however, the study that this review article refers to does not have any evidence on this issue.