Cystic Fibrosis and the Gastrointestinal tract Flashcards
What is the cystic fibrosis transmembrane conductance regulator (CFTR)?
- a membrane protein and chloride channel
- encoded by the CFTR gene
- this is mutated in cystic fibrosis
What type of mutation, in terms of how affected genes are is cycstic fibrosis?
- point mutation
- a single nucleotide is affected
What is the most common genetic mutation in cycstic fibrosis?
- deltaF508
In cystic fibrosis are the mutations in the CFTR that patients have on their 2 different alleles homozygous or heterozygous?
- can be both
- homozygous (2 of the same gene)
- heterozygous (2 different genes) - RARER
In cystic fibrosis mutations in the CFTR affect the membrane proteins ability to pump chloride (Cl-). In the body this specifically affects something that is produced by epithelial cells, and therefore affects very specific tissues. What is it that is affected in cystic fibrosis?
- mucous]
- lungs, pancreas, GIT
In cystic fibrosis mutations in the CFTR affect the membrane proteins ability to pump chloride (Cl-). In the body this specifically affects mucous that is produced by epithelial cells, and therefore affects very specific tissues. How can this affected the GIT?
- affects bicarbonate and fluid levels in GIT
In cystic fibrosis mutations in the CFTR affect the membrane proteins ability to pump chloride (Cl-). In the body this specifically affects mucous that is produced by epithelial cells, and therefore affects very specific tissues. How can this affected the pancreas?
- exocrine and endocrine secretions are sticky
- leads to pabcreatic insufficiency
In cystic fibrosis mutations in the CFTR affect the membrane proteins ability to pump chloride (Cl-). In the body this specifically affects mucous that is produced by epithelial cells, and therefore affects very specific tissues. How can this affected failure to develop?
- canalisation, which is tube formation is impaired if mucous is affected
- the intestine in utero (causing neonatal meconium (dark stricky mucous) ileus)
- essentially blocking of GIT
Can cystic fibrosis present as acute or chronic only?
- both
Does cystic fibrosis present at any specific age?
- any age
- generally diagnosed early though
As the GIT and pancreas are affected, what can this lead to?
- malabsotpion of nutrients
If a patient presents at A&E with cystic fibrosis and acute abdomianl pain, what could be some other differential diagnosis that are associated with cystic fibrosis?
- pancreatitis (inflammation of pancreas)
- distal intestinal obstructive syndrome (DIOS)
- cholecystitis (gallbladder inflammation)
- gastro-oesophageal reflux disease (GORD)
- Cystic Fibrosis Liver Disease (CFLD)
- colorectal cancer
If a patient presents at A&E with cystic fibrosis and acute abdomianl pain, what could be some other differential diagnosis that are NOT associated with cystic fibrosis?
- IBS
- appendicitis
- gastritis
- gastroenteritis
How can cystic fibrosis be inherited?
- autosomal recessive (no sex chromosomes)
- patients need a mutated gene from both parents
- if only one gene they are a carrier
If a patient presents at A&E with cystic fibrosis and acute abdomianl pain, what could be some of the tests run that could help identify the problem?
- bloods
- chest X-ray
- abdominal CT scan
What is distal intestinal obstruction syndrome (DIOS)
- a complication of cystic fibrosis
- bowel becomes partially or completely blocked
- generallty occurs where the small bowel joins the large bowel.
Distal intestinal obstruction syndrome (DIOS) is a complete or partial blockage of the GIT that is a complication of cystic fibrosis. What is the main cause of this?
- thick “stool” blocks intestinal tube
Distal intestinal obstruction syndrome (DIOS) is a complete or partial blockage of the GIT that is a complication of cystic fibrosis that is caused by thick “stool” blocking the intestinal tube. Why does thick stool form in cystic fibrosis?
- lack of enzymes (exocrine – amylase, lipase, protease)
- dehydration
- narrow of GIT, ileocaecal area particularly affected
- terminal ileum leads to vitamin B12 absorption
- valve dysfunction leads to “dumping” syndrome from ileum to colon
- can present like an appendicitis
Distal intestinal obstruction syndrome (DIOS) is a complete or partial blockage of the GIT that is a complication of cystic fibrosis that is caused by thick “stool” blocking the intestinal tube. Another cause of obstruction, but less common is intussusception. What is intussusception?
- part of the intestine slides into an adjacent part of the intestine
- very dangerous
How can we treat distal intestinal obstruction syndrome and/or intussusception?
- rehydration
- laxatives
- enzyme (Creon)
- surgery
How can cystic fibrosis cause Cholecystitis?
- CFTR is highliy expressed in liver and biliary tree
- can lead to narrowing bilary tree or mini gall bladder
- bile scretions will be thick and sticky
Cystic fibrosis can cause Cholecystitis due to the high expression of the CFTR in the liver and biliary tree. This can lead to narrowing of the bilary tree or a mini gall bladder. What can CF due to bile secretions and increase the risk of?
- bile scretions will be thick and sticky
- increased risk of gall stones and blockage of bilary tree
Cystic fibrosis can cause Cholecystitis due to the high expression of the CFTR in the liver and biliary tree. This can lead to narrowing of the bilary tree or a mini gall bladder. The bile scretions can be thick and sticky, increasing the risk of gall stones and blockage of bilary tree. What can this then increase the risk of?
- increased risk from bacterial endotoxins
Cystic fibrosis can cause Cholecystitis due to the high expression of the CFTR in the liver and biliary tree. This can lead to narrowing of the bilary tree or a mini gall bladder. The bile scretions can be thick and sticky, increasing the risk of gall stones and blockage of bilary tree and increase the risk of bacterial infections. What else can happen to bile once it has been pumped into the GIT?
- lost in stool as cannot be absorbed
- causes fat/bile acid diarrhoea
