Cystic fibrosis Flashcards
Is cystic fibrosis a heritable disease or not?
Yes it is
What is the inheritance pattern of cystic fibrosis?
Autosomal recessive
What chromosome is affected in cystic fibrosis? What part of it?
Chromosome 7
q arm
What gene is affected in cystic fibrosis?
Cystic fibrosis transmembrane conductance regulator (CFTR) gene
What protein is affected in cystic fibrosis?
CTFR protein
How is the CTFR protein affected in cystic fibrosis?
Does not fold properly
Is not transported to the membrane, so it’s degraded
Where is the CFTR protein normally located?
Outer membrane of cells in lungs, pancreas, sweat glands
What is the function of the CTFR protein in the lungs and pancreas?
Transports chloride ions into secretions
water follows chloride ions
makes secretions thinner
What happens to secretions in the lungs and pancreas with cystic fibrosis?
Chloride ions are not transported into secretions
water does not follow
secretions aret hick
How does thick secretions affect the lungs?
Cilia cannot waft mucus up to oropharynx
builds in up in bronchi and bronchioles
What is a complication of accumulating thick mucus in the bronchi and bronchioles?
Traps bacteria
more prone to infection
Leads to bronchiecstasis
How do thick secretions affect the pancreas?
Block pancreatic duct
What are the complications of blocking the pancreatic duct?
Malabsorption
Steatorrhoea
Acute pancreatitis
Why does blocking the pancreatic duct cause malabsorption?
Pancreatic enzymes do not reach duodenum
digestion is not completed
reduced absorption
How does malabsorption present in a child with cystic fibrosis?
Failure to thrive
Why does blocking the pancreatic duct cause steatorrhoea?
Pancreatic lipase does not reach duodenum
fats are not digested
excreted in faeces
What is the function of the CTFR protein in sweat glands?
Transports chloride ions from the sweat back into the cells
fewer chloride ions remaining in sweat
What happens to sweat with cystic fibrosis?
Chloride ions are not transported out of sweat back into cells
more chloride ions in sweat
How is cystic fibrosis diagnosed?
History of symptoms, family history
Newborn screening
How are newborns screened for cystic fibrosis?
Heel prick test
If the above is positive, then sweat test
How does the heel prick test diagnose cystic fibrosis?
Looks at levels of IRT in the blood
pancreatic enzyme
raised with pancreatic damage
How does the sweat test diagnose cystic fibrosis?
High concentration of chloride ions in sweat
How does cystic fibrosis present in a newborn?
Meconium ileus
What is meant by meconium ileus?
Thickened faeces
give intestinal obstruction
What are the signs of meconium ileus?
Abdominal distension
Bilious vomiting
Delay in passing meconium, first faeces
What is a specific sign/symptom of cystic fibrosis in males?
Infertility
How does cystic fibrosis cause infertility in males?
Absence of vas deferens
