[DrSeddik]

A 21 year old male patient comes in with a chest problem. For the past years he has been coughing very large volumes of sputum. Now he has high fever, haemoptysis and the chest x ray shows bronchopneumonic opacities. Sputum culture is positive for Pseudomonas aeuroginosa. He says that he has problem with diseases since he was born as he was told that he has had GI troubles. He was also recently diagnosed with a nasal polyp. His sweat chloride is elevated. What would you tell him regarding his condition:

a- he shouldn't worry about fertility problems, because he has normal cilliary function
b- he probably has lower than normal chloride in his intestinal secretions
c- his parents should not worry about their offspring as their chances of getting the disease are negligible
d- the condition results from a frame shifting mutation
e- the condition is due to splice site mutation

 

[khanar]

Nice one
I'd choose option B as the correct answer

 

[khanar]

Is that cystic fibrosis?

 

[ashishkabir]

Is that cystic fibrosis?

Yup and it's most commonly a point mutation in Chomosome 7q position 508, not frameshift or splice site

 

[DrSeddik]

The patient has cystic fibrosis, which lead to bronchiectasis now. Pseudomonas are common pathogens in these patients, next in line is staph. areus pneumonia. He had meconium ileus as a child. If you want to remember one thing about this disease, it's thick secretions which causes all the symptoms.

The disease renders CFTR (CF Transmembrane conductance regulator) non functional. However the function of this proteins is tissue specific; it normally helps reabsorbing NaCl in sweat glands, dysfunction causes sweat to be hypertonic, the basis of sweat chloride test. In intestinal and airway it helps secretion of Cl, and sodium is reabsorbed into the luminal cells. In CF Cl secretion is defective, the negative charge inside the luminal cells is higher leading to higher Na (and consecutively water) rebsorption.

a- Kartagner syndrom is another cause of bronchiectasis which is usually associated with infertility due to immotile cillia. CF is associated with infertility due to "dehydrated" seminal secretion and atresia of the vas
b- correct answer
c- CF is AR so the minimal chance of getting the disease in another offspring is 25% (if both parents are carriers)
d- and e- as been said, CF is most commonly due to 3 nucleotide deletion that code for Phenylalanine at amino acid position number 508 in CFTR protein
NB info sources are Robbins basic pathology 8th edition and goljan.. I have an explaining picture but I can't size it down!?

thanks for participating...