NADPH; G6PD versus Chronic Granulamatous Disease - USMLE Forums
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  #1  
Old 09-21-2012
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Biochemistry NADPH; G6PD versus Chronic Granulamatous Disease

Blood sample from a 22 yr old male with infection shows leukocytosis. Differential Leukocyte count shows 58% neutrophils, 39% lymphocytes, 2% eosinophils, 0% basophils. Peripheral smear shows red cells with intracellular bodies. A test is done where leukocytes are exposed to Nitroblue tetrazolium but the cells remain colorless. What could be the most likely cause of this patients presentation?

A. Chronic granulomatous disease
B. G6PD deficiency
C. Myeloperoxidase deficiency
D. Chediek higashi syndrome
E. Malaria
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Old 09-21-2012
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Arrow A

A . Chronic granulomatous disease
Lack of NADPH oxidase results in decreased reactive O2 species and absent respiratory burst and negative NBT test.
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Old 09-22-2012
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CGD
if respiratory burst is present (not in CGD lack of NADPH oxidase so less superoxide) colorless NBT dye converts to blue color.
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  #4  
Old 09-22-2012
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I would say B
(RBC includions)
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Old 09-22-2012
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CGD........
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  #6  
Old 09-22-2012
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Default b

Peripheral smear shows red cells with intracellular bodies-->G6PD
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Old 09-22-2012
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Still colorless NBT and red cell with intercellular bodies
B. G6PD deficiency
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Old 09-22-2012
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B.G6PD deficiency..like CGD there will be lack of NADPH..no reactive o2 species no change in colour of NBT..PBS findings r in favour of B.
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Old 09-22-2012
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Quote:
Originally Posted by koolkiller88 View Post
Still colorless NBT and red cell with intercellular bodies
B. G6PD deficiency
how you will see intracelular bodies in RBC's because with oxidative stres hemolysis ocurs??
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Quote:
Originally Posted by koolkiller88 View Post
Still colorless NBT and red cell with intercellular bodies
B. G6PD deficiency
how you will see intracelular bodies in RBC's because with oxidative stres hemolysis ocurs??
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Old 09-22-2012
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http://en.wikipedia.org/wiki/Nitro_b...olium_chloride
Nitro blue tetrazolium is a chemical compound composed of two tetrazole moieties. It is used in immunology for sensitive detection of alkaline phosphatase (with BCIP). NBT serves as the oxidant and BCIP is the AP-substrate (and gives also dark blue dye).
The NBT/BCIP reaction is also used for colorimetric/spectrophotometric activity assays of oxidoreductases. One application is in activity stains in gel electrophoresis, such as with the mitochondrial electron transport chain complexes.
Nitro blue tetrazolium is used in a diagnostic test, particularly for chronic granulomatous disease and other diseases of phagocyte function. A disease where there is a defect in NADPH oxidase, therefore the phagocyte is unable to make the reactive oxygen species or radicals required for bacterial killing and results in bacteria thriving within the phagocyte. The higher the blue score, the better the cell is at producing reactive oxygen species.
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Old 09-22-2012
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RBCs have heinz bodies which are the result of Hb denaturation from oxidative stress (O2 free radicals not neutralized due to lack of NADPH)
Hemolysis is extravascular so RBCs must pass through spleen to be removed and before they do so are circulating in blood
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yes, the most appropriate answer is B) G6PD deficiency

from the pt. history we can know that RBC with intracellular bodies---which represent heinz bodies formed due to oxidation in stress conditions....

nitroblue tetrazolium remains colorless indiactes negative NBT test --which is most commonly associate with NADPH oxidase deficiency(CGD)....in NADPH oxidase deficiency superoxide radicals are not formed and cannot form H2O2..so the test remains colorless....

HMP shunt pathway is the primary source for NADPH...so in patients with G6PD deficiency...NADPH cannot be produced and ultimately enzymes cannot be formed leading to deficiency of NADPH oxidase leading to CGD.......





A low level of NADPH, the cofactor required for superoxide synthesis, can lead to CGD. This has been reported in women/men who arehomozygous for the genetic defect causing glucose-6-phosphate dehydrogenase deficiency (G6PD), which is characterised by reduced NADPH levels.[citation needed]

source------------wikipedia
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  #14  
Old 09-22-2012
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Quote:
Originally Posted by riya rai View Post
how you will see intracelular bodies in RBC's because with oxidative stres hemolysis ocurs??
Ya riya you are right.
My mistake
It should be CGD
As nitroblue tetrazolium is a colorless liquid and changes its color in the presence of H2O2.
As CGD Patients doesn't produce H2O2 so NBT will remain colorless.

"Peripheral smear shows red cells with intracellular bodies." made me confused. So is it Heinz bodies?
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Quote:
Originally Posted by koolkiller88 View Post
Ya riya you are right.
My mistake
It should be CGD
As nitroblue tetrazolium is a colorless liquid and changes its color in the presence of H2O2.
As CGD Patients doesn't produce H2O2 so NBT will remain colorless.

"Peripheral smear shows red cells with intracellular bodies." made me confused. So is it Heinz bodies?
koolkiller88....i guess you are quite lucky as your logical thinking always chooses the right option.....
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  #16  
Old 09-22-2012
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Quote:
Originally Posted by venky2600 View Post
koolkiller88....i guess you are quite lucky as your logical thinking always chooses the right option.....
Haha hope this luck continues upto real exam.
;-)


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Old 09-22-2012
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Quote:
Originally Posted by venky2600 View Post
yes, the most appropriate answer is B) G6PD deficiency

from the pt. history we can know that RBC with intracellular bodies---which represent heinz bodies formed due to oxidation in stress conditions....

nitroblue tetrazolium remains colorless indiactes negative NBT test --which is most commonly associate with NADPH oxidase deficiency(CGD)....in NADPH oxidase deficiency superoxide radicals are not formed and cannot form H2O2..so the test remains colorless....

HMP shunt pathway is the primary source for NADPH...so in patients with G6PD deficiency...NADPH cannot be produced and ultimately enzymes cannot be formed leading to deficiency of NADPH oxidase leading to CGD.......





A low level of NADPH, the cofactor required for superoxide synthesis, can lead to CGD. This has been reported in women/men who arehomozygous for the genetic defect causing glucose-6-phosphate dehydrogenase deficiency (G6PD), which is characterised by reduced NADPH levels.[citation needed]

source------------wikipedia

forgot to mention abt the other options

a) CGD-------in NADPH oxidase deficiency too...nitroblue tetrazolium test remains colorless but the red cell with intracellular bodies(heinz bodies) make the G6PD deficiency as the most correct diagnosis

c) MPO deficiency-----------in MPO deficiency, NBT test is normal(since, respiratory burst of o2 to H2O is intact)...MPO helps in fromation of HOCL ions from H2O2

D)chediak hegashi------defect in protein traffiking gene...impaired lysosome and phagosome fusion with giant granules in neutrophils are seen

e) malaria-----caused by plasmodium species charectarised by schuffner dots and ringed schizonts...
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  #18  
Old 09-22-2012
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Default G6PD

G6PD deficiency is an inherited condition in which the body doesn't have enough of the enzyme glucose-6-phosphate dehydrogenase, or G6PD, which helps red blood cells (RBCs) function normally. This deficiency can cause hemolytic anemia, usually after exposure to certain medications, foods, or even infections.
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  #19  
Old 09-30-2012
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Quote:
Originally Posted by koolkiller88 View Post
Ya riya you are right.
My mistake
It should be CGD
As nitroblue tetrazolium is a colorless liquid and changes its color in the presence of H2O2.
As CGD Patients doesn't produce H2O2 so NBT will remain colorless.

"Peripheral smear shows red cells with intracellular bodies." made me confused. So is it Heinz bodies?
http://en.wikipedia.org/wiki/Nitro_b...olium_chloride
Nitro blue tetrazolium is a chemical compound composed of two tetrazole moieties. It is used in immunology for sensitive detection of alkaline phosphatase (with BCIP). NBT serves as the oxidant and BCIP is the AP-substrate (and gives also dark blue dye).

acording to above theory i would like to clear mine concept with that stres test what wil be the efect on RBC's they wil not hemolysed?? ya i know that intracelular bodies seen in this condition and NBT test will remain negative
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  #20  
Old 09-30-2012
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G6PD Deficiency.

Firstly, NBT is negative which means NADPH oxidase is not working.
Secondly, the RBCs(NOT phagocytes) have intracellular bodies(Heinz bodies).
Had the bodies been in Phagocytes, CGD could have been the answer.
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  #21  
Old 09-30-2012
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Thanks.. For the explanation..
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Old 08-11-2014
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So those who have g6pd prone to get cgd right?
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