Rare mutations (RMs) occur in only a few patients with limited reported clinical data. One example of these types of mutations is A455E. Many mutations in fact produce truncated proteins (Class I mutations) or misfolded proteins (Class II mutations like DF508 or N1303K)that actually cannot reach the cell surface, and need another molecule (a corrector) to rescue the CFTR protein and let it positionate in the right place. Like other class II mutations, ΔF508 CFTR is retained in the ER, incompletely glycosylated, and rapidly degraded in proteasomes . Clinical information in this database relates only to the details of discovery of specific mutations. These changes are grouped into 6 classes. CFTR2 is a website that provides information for patients, researchers, and the general public about specific variants in what is commonly referred to as the cystic fibrosis (CF) gene. If Phe508del-CFTR is expressed at the apical membrane — for example, following monotherapy with a CFTR corrector such as lumacaftor — it has been demonstrated that the chloride channel has a reduced probability of being open, operating as a class III gating CFTR mutation [15, 16]. This document was developed as a special control to support the classification of CFTR (cystic fibrosis transmembrane conductance regulator) gene mutation detection systems into class II … The pancreas is one of the primary organs affected by dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) protein. If this defect is overcome then the protein can form a functional channel. For each variant or variant combination included in the database, the website will provide information about: 1. More than 1,000 mutations in the CFTR gene have been identified in people with cystic fibrosis. This can be brought about by overexpression of CFTR or by culturing cells at > 30 oC. Finally, class V mutations in the CFTR gene produce CFTR protein, but in insufficient and low quantity. The DF508 accounts for 66 % of the mutations, 40 % of these patients are compound heterozygotes with DF508 on one allele and another mutation of CFTR gene on the other chromosome. Whether the variant or variant combination is CF-causing, and. Belgian CF-Registry 2013 data were analyzed to identify CF with at least 1 RM (CF+RM). People with CF who have some residual CFTR function (Classes 4, 5 & 6) tend to have milder or later onset of symptoms. It also explains the range of responses individuals get from the same treatments. Generally, the pulmonary function, the age of onset of the disease, and the amount of chloride salt are all related to a particular genotype. CF Mutation Classes The image below shows how a protein is made from DNA.