Cystic fibrosis

Question 1

Is cystic fibrosis a heritable disease or not?

Answer 1

Yes it is

Question 2

What is the inheritance pattern of cystic fibrosis?

Answer 2

Autosomal recessive

Question 3

What chromosome is affected in cystic fibrosis? What part of it?

Answer 3

Chromosome 7

q arm

Question 4

What gene is affected in cystic fibrosis?

Answer 4

Cystic fibrosis transmembrane conductance regulator (CFTR) gene

Question 5

What protein is affected in cystic fibrosis?

Answer 5

CTFR protein

Question 6

How is the CTFR protein affected in cystic fibrosis?

Answer 6

Does not fold properly

Is not transported to the membrane, so it’s degraded

Question 7

Where is the CFTR protein normally located?

Answer 7

Outer membrane of cells in lungs, pancreas, sweat glands

Question 8

What is the function of the CTFR protein in the lungs and pancreas?

Answer 8

Transports chloride ions into secretions
water follows chloride ions
makes secretions thinner

Question 9

What happens to secretions in the lungs and pancreas with cystic fibrosis?

Answer 9

Chloride ions are not transported into secretions
water does not follow
secretions aret hick

Question 10

How does thick secretions affect the lungs?

Answer 10

Cilia cannot waft mucus up to oropharynx

builds in up in bronchi and bronchioles

Question 11

What is a complication of accumulating thick mucus in the bronchi and bronchioles?

Answer 11

Traps bacteria
more prone to infection

Leads to bronchiecstasis

Question 12

How do thick secretions affect the pancreas?

Answer 12

Block pancreatic duct

Question 13

What are the complications of blocking the pancreatic duct?

Answer 13

Malabsorption

Steatorrhoea

Acute pancreatitis

Question 14

Why does blocking the pancreatic duct cause malabsorption?

Answer 14

Pancreatic enzymes do not reach duodenum
digestion is not completed
reduced absorption

Question 15

How does malabsorption present in a child with cystic fibrosis?

Answer 15

Failure to thrive

Question 16

Why does blocking the pancreatic duct cause steatorrhoea?

Answer 16

Pancreatic lipase does not reach duodenum
fats are not digested
excreted in faeces

Question 17

What is the function of the CTFR protein in sweat glands?

Answer 17

Transports chloride ions from the sweat back into the cells

fewer chloride ions remaining in sweat

Question 18

What happens to sweat with cystic fibrosis?

Answer 18

Chloride ions are not transported out of sweat back into cells
more chloride ions in sweat

Question 19

How is cystic fibrosis diagnosed?

Answer 19

History of symptoms, family history

Newborn screening

Question 20

How are newborns screened for cystic fibrosis?

Answer 20

Heel prick test

If the above is positive, then sweat test

Question 21

How does the heel prick test diagnose cystic fibrosis?

Answer 21

Looks at levels of IRT in the blood
pancreatic enzyme
raised with pancreatic damage

Question 22

How does the sweat test diagnose cystic fibrosis?

Answer 22

High concentration of chloride ions in sweat

Question 23

How does cystic fibrosis present in a newborn?

Answer 23

Meconium ileus

Question 24

What is meant by meconium ileus?

Answer 24

Thickened faeces

give intestinal obstruction

Question 25

What are the signs of meconium ileus?

Answer 25

Abdominal distension

Bilious vomiting

Delay in passing meconium, first faeces

Question 26

What is a specific sign/symptom of cystic fibrosis in males?

Answer 26

Infertility

Question 27

How does cystic fibrosis cause infertility in males?

Answer 27

Absence of vas deferens