Cystic fibrosis

Question 1

Is cystic fibrosis a autosomal recessive or dominant disease?

Answer 1

It is autosomal recessive

Question 2

What gene is affected?

Answer 2

CFTR gene(cystic fibrosis transmembrane conductance regulator)

Question 3

What is the exact mutation that occurs on the CFTR gene?

Answer 3

-delta F508(deletion of phenylalanine 508th amino acid on chromosome 7

Question 4

What is often the first clinical sign of cystic fibrosis?

Answer 4

Inability to pass meconium

This is known as meconium ileus

Question 5

The F508 gene mutation does what to the CFTR gene?

Answer 5

-it leads to the production of defective chloride channels on the cell membranes of exocrine glands

Question 6

What systems are affected by cystic fibrosis?

Answer 6

The lung
Digestive system
Sweat glands

Question 7

What is the average lifespan of cystic fibrosis?

Answer 7

39 years

Question 8

The defective CFTR gene codes for what protein?

Answer 8

Misfolded proteinwhich is then retained in the rough endoplasmic reticulum for degradation

Question 9

What is the main difference between exocrine glands and sweat glands?

Answer 9

1. In sweat glands the chloride channels usually transport chloride from the lumen to inside the cell but because there is a mutation the chloride stays in the lumen and accumulates Na causing the salty taste
2. In exocrine glands the chloride channel would transport the chloride from intracellular to the lumen but because this is defective and so will cause accumulation of secretions leading to organ damage

Question 10

What are the respiratory clinical features of cystic fibrosis?

Answer 10

1. Chronic obstructive disease with bronchiectasis
2. Chronic sinusitis with nasal polyps
3. Chronic recurrent productive cough and infections caused by staph aureas(gram positive) and pseudomonas aerigenosa (gram negative)

Question 11

What happens to the sweat glands?

Answer 11

Salt tasting when kissing baby

Question 12

What happens to the pancreas?

Answer 12

-pancreatitis
-pancreatic insufficiency
Causing steatorrhea, malabsorption, abdominal distension, fat soluble vitamin deficiency

Question 13

What happens in the gastrointestinal system?

Answer 13

• meconium ileus

- failure to thrive

Question 14

What is the best test for cystic fibrosis?

Answer 14

1.The chloride sweat test
Two tests above 60 mmol/l points to CF
2. Stool elastase or stool chemotrypsin

Question 15

What is the management of cystic fibrosis?

Answer 15

1. Chest physiotherapy
2. Bronchodilator
3. High dose of ibuprofen has been shown to decrease the disease progression
4. Vitamin supplementation of vitamin ADEK
5. CFTR modulators-ivacaftor, lumacaftor

Question 16

What are the complications of cystic fibrosis?

Answer 16

Respiratory- haemoptysis, pulmonary emphysema

Gastrointestinal-meconium ileus

Question 17

What genetic mutation occurs mostly in black children?

Answer 17

320+1G-A

Question 18

How does cystic fibrosis present in neonates?

Answer 18

1. Meconium ileus causing bowel obstruction
2. Meconium peritonitis
3. Prolonged Cholestatic jaundice

Question 19

How do children in the first year of life present with cystic fibrosis?

Answer 19

1. Recurrent respiratory infections
2. Prolonged and recurrent wheezing and failure to thrive
3. Malabsorption of nutrients(due to pancreatic insufficiency)
4. Large smelly sand bulky stool with fat globules
5. Hyponatraemic dehydration due to loss of salt
6. Diabetes mellitus

Question 20

How does cystic fibrosis present in adults?

Answer 20

Infertility

Question 21

Which organism do we need to prevent in cystic fibrosis of the lung?

Answer 21

-pseudomonas aeruginosa leading to the accelerated loss of lung function