Types of Cystic Fibrosis

Contents

Cystic Fibrosis: Types list

The list of types of Cystic Fibrosis mentioned in various sources includes:

Over 500 different cystic fibrosis mutations exist
Delta F508 mutation cystic fibrosis
R117H mutation cystic fibrosis

Curable Types of Cystic Fibrosis:

Pneumothorax related to cystic fibrosis
Nasal polps related to cystic fibrosis
Chronic sinusitis related to cystic fibrosis
Meconium ileus related to cystic fibrosis
Intussusception related to cystic fibrosis
Undescended testis associated to cystic fibrosis
Hydrocele associated with cystic fibrosis

Rare Types of Cystic Fibrosis:

Nasal polyps related to cystic fibrosis
Pancreatic insufficiency related cystic fibrosis
Sinusitis related cystic fibrosis
Bronchiectasis related cystic fibrosis
Intussusception related to cystic fibrosis
Undescended testis associated to cystic fibrosis
Hydrocele associated with cystic fibrosis

Types discussion:

Cystic Fibrosis Research Directions: NIDDK (Excerpt)

Different Mutations Have Different Effects

In CF patients, depending on the specific mutation, the CFTR protein may be reduced or missing from the cell membrane, or may be present but not function properly. In some mutations, synthesis of CFTR protein is interrupted, and the cells produce no CFTR molecules at all.

Although about 500 mutations have been identified, one mutation is particularly common and occurs in 70 percent of all defective CF genes. This most common mutation is called delta F508 because the CFTR protein it encodes is missing a single amino acid at position 508. Almost half of all CF patients have inherited this mutation from both their parents. Because of its high prevalence, the consequences of mutation delta F508 have been studied in detail. This mutation affects CFTR processing in the cell and prevents it from assuming its functional location in the cell membrane. Newly synthesized CFTR protein normally is modified by the addition of chemical groups, folded into the appropriate shape and escorted by molecular chaperones to the cell surface. The cell has quality control mechanisms to recognize and destroy improperly processed proteins. However, under certain conditions, a small amount of this imperfect CFTR is incorporated into the cell membrane, where it appears to have a defect in opening and closing and regulating chloride flow.

Other mutations produce defects in CFTR that do not impair its synthesis, modification or integration into the cell membrane. However, with some of these mutations the CFTR fails to respond normally to the signals within the cell that control the channel's opening and closing. With other mutations, the CFTR protein reaches the cell membrane and responds properly to intracellular signals, but when the channel opens, chloride flow out of the cell is inadequate.

Although all these different mutations impair chloride transport, the consequences for the patients vary. For example, patients with mutations causing absent or markedly reduced CFTR protein in the cell membrane may have more severe disease with compromised pancreatic function and require pancreatic enzyme supplements. Patients with mutations in which CFTR is present in the cell membrane, but with altered function, may have adequate pancreatic function. Scientists have been less successful at correlating specific mutations with severity of lung disease than with pancreatic function.

Patients with the delta F508 mutation on both CFTR gene copies usually develop early-onset pancreatic insufficiency combined with varying degrees of lung disease. A CFTR mutation called R117H, which also is relatively common, produces a partially functional CFTR protein. This "mild" mutation, in combination with a severe mutation such as delta F508, usually causes CF with preserved pancreatic function but varying lung disease. Some men with the R117H mutation are infertile because they lack the vas deferens, but have no other CF symptoms. (Source: excerpt from Cystic Fibrosis Research Directions: NIDDK)

NHLBI, Facts About Cystic Fibrosis: NHLBI (Excerpt)

The mutation involved in CF causes the deletion of three of the base pairs in the gene. This in turn, causes a loss in the CFTR protein of an amino acid (the building blocks of proteins). Because phenylalanine is located in position 508 of the protein chain, this mutant protein is called deltaF508 CFTR.

However, deltaF508 CFTR accounts for only 70-80 percent of all CF cases. Various other mutations-over 400 at the last count-seem to be responsible for the remaining CF cases. Differences in disease patterns seen in individuals and families probably result from the combined effects of the particular mutation and various, but still unknown, factors in the CF patient and his or her environment. (Source: excerpt from NHLBI, Facts About Cystic Fibrosis: NHLBI)