Why is there pancytopenia with paroxysmal nocturnal hemoglobinuria?

[str8flexed]

^^^^

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[braluk]

Decay Accelerating factor (a glycosylphosphatidylinositol (GPI)-anchored membrane protein) is responsible for preventing cells from getting tagged and destroyed by complement during night-time rest (which is usually characterized by a mild respiratory acidosis). I think it basically stops C3 from fixing onto cell membranes (I guess mild acidosis typically represents inflammation so you're more likely subject to complement fixation?). Anyhow, if you have a defective DAF all your cells will be subject to hemolysis. It's been a while since I've studied up on this so don't take my word 100% unless someone else confirms.

 

[McGillGrad]

Why does the sun come up every morning? No one will ever know the real reason.

 

[jigga]

It is clonal stem disorder. It affects all cell lines.
Somatic mutation in the gene PIG-A results in impaired synthesis of GPI anchor which increases sensitivity to complement mediated lysis. GPI anchor is required for the fixation of protective protiens (eg CD 55, CD 59, CD 8) on to the cellular surfaces. DAF is another example of a GPI linked protein which normally inhibits the complement cascade by breaking down C3 convertase.

 

[str8flexed]

I guess what I'm wonder is: is GPI/DAF present on all normal cells (including WBC and platelets), preventing their destruction by complement?

 

[braluk]

It would appear so, yes. And not to sound preachy but you need to really go out and look up these answers yourself, it's not hard to find them online and you learn better by being proactive in your learning and you get your answer right away. Just wishing you to do the best

 

[SimonSez]

I agree with Braluk. One of our professors once told us that you should never ask a question to which the answer can be found by a little effort/research on your part. You learn better that way and you don't come off as being too lazy to find out the answer yourself.
So rather than asking questions about Pneumothorax, ST elevation or PNH you should do some reading and figure it out on your own. If after doing this you still can't understand something then by all means feel free to ask.

 

[str8flexed]

I agree with Braluk. One of our professors once told us that you should never ask a question to which the answer can be found by a little effort/research on your part. You learn better that way and you don't come off as being too lazy to find out the answer yourself.
So rather than asking questions about Pneumothorax, ST elevation or PNH you should do some reading and figure it out on your own. If after doing this you still can't understand something then by all means feel free to ask.

I have looked for several minutes for each without satisfactory answers. You guys are normally smart and provide accurate explanations. If I asked everything, I would be posting 20x a day.

 

[McGillGrad]

I have looked for several minutes for each without satisfactory answers. You guys are normally smart and provide accurate explanations. If I asked everything, I would be posting 20x a day.

How long so you have until your exam?

 

[SimonSez]

I have looked for several minutes for each without satisfactory answers. You guys are normally smart and provide accurate explanations. If I asked everything, I would be posting 20x a day.

I know it can be overwhelming. The volume of information that we are expected to know is incredible.
From your questions you seem to be interested in the "why" (i.e mechanism). This is excellent on your part because it is so easy to just take things at face value and move on. It shows that you are thinking. Good luck.

 

[str8flexed]

My exam is tomorrow. Took a NBME several days ago and got a 247. Hoping to break 250. I'll post back later.............

 

[McGillGrad]

My exam is tomorrow. Took a NBME several days ago and got a 247. Hoping to break 250. I'll post back later.............

 

[str8flexed]

Nope, not fraudin.

 

[McGillGrad]

Well, that shut me up!

Wow, Congrats!