Cause of Peripheral lymphoid Disorder in Infant - USMLE Forums
USMLE Forums Logo
USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
Home
USMLE Articles
USMLE News
USMLE Polls
USMLE Books
USMLE Apps
Go Back   USMLE Forums > USMLE Step 1 Forum

USMLE Step 1 Forum USMLE Step 1 Discussion Forum: Let's talk about anything related to USMLE Step 1 exam


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 06-05-2012
beka-CTS's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 763
Threads: 77
Thanked 1,369 Times in 349 Posts
Reputation: 1379
Question Cause of Peripheral lymphoid Disorder in Infant

An 18-month-old infant has had a history of recurrent bacterial and viral infections. The child has failure to thrive, developmental delay, and tremors. Physical exam shows a lack of peripheral lymphoid tissue. Blood work shows lymphopenia, but normal levels of B-cells and circulating immunoglobulins. This child most likely has a defect in which of the following enzymes?



(A) Hypoxanthine guanine phosphoribosyltransferase (HGPRT)

(B) Adenine phosphoribosyltransferase (APRT)

(C) Adenosine deaminase (ADA)

(D) Adenosine kinase

(E) Purine nucleoside phosphorylase


__________________
Step 1 - 244 [✔] Step 2 CK - 246 [✔] Step 2 CS [✔] Step 3 - 228 [✔] Match [EMORY SOM] YOG: 2013, 4 Months of USCE University Hospital
Reply With Quote Quick reply to this message



  #2  
Old 06-05-2012
Rookie's Avatar
USMLE Forums Guru
 
Steps History: 1+CK+CS
Posts: 394
Threads: 40
Thanked 218 Times in 99 Posts
Reputation: 228
Default

Developmental delay and tremors(due to basal ganglion involvement) I would go with HGPRT deficiency

What bout T cell deff alone ??
__________________
The Journey of thousand miles begins with a single step.
Reply With Quote Quick reply to this message
  #3  
Old 06-06-2012
beka-CTS's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 763
Threads: 77
Thanked 1,369 Times in 349 Posts
Reputation: 1379
Correct Answer

The answer is E: Purine nucleoside phosphorylase. The child has purine nucleoside phosphorylase deficiency, which, for reasons not yet fully elucidated, specifi cally reduces T-cell counts but not B-cells. Purine nucleoside phosphorylase is one of the salvage enzymes that converts guanosine or inosine to the free base plus ribose-1-phosphate (adenosine is not a substrate for this enzyme). HGPRT deficiency leads to Lesch–Nyhan syndrome, whose symptoms are quite different (there is no immune deficiency with an HGPRT defect). APRT deficiency leads to a buildup of an insoluble metabolite (2,8-dihydroxyadenine) that precipitates in the kidney and will lead to renal failure. ADA deficiency will lead to an immune disorder,
but in ADA deficiency,both B and T cells are deficient.
An adenosine kinase deficiency has not been reported in humans.
__________________
Step 1 - 244 [✔] Step 2 CK - 246 [✔] Step 2 CS [✔] Step 3 - 228 [✔] Match [EMORY SOM] YOG: 2013, 4 Months of USCE University Hospital
Reply With Quote Quick reply to this message
The above post was thanked by:
..sharma (06-06-2012)
 
  #4  
Old 06-06-2012
Rookie's Avatar
USMLE Forums Guru
 
Steps History: 1+CK+CS
Posts: 394
Threads: 40
Thanked 218 Times in 99 Posts
Reputation: 228
Default Good Q

So far had known about HGPRT n ADA deficiency..

What is the source of this Q?
__________________
The Journey of thousand miles begins with a single step.
Reply With Quote Quick reply to this message
  #5  
Old 06-06-2012
beka-CTS's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 763
Threads: 77
Thanked 1,369 Times in 349 Posts
Reputation: 1379
Default

Quote:
Originally Posted by Rookie View Post
So far had known about HGPRT n ADA deficiency..

What is the source of this Q?
I found it in lippincott's questions and answers of biochemistry.

i had no idea about it. thought it was ADA, but couldn't understand T cell problems only.
__________________
Step 1 - 244 [✔] Step 2 CK - 246 [✔] Step 2 CS [✔] Step 3 - 228 [✔] Match [EMORY SOM] YOG: 2013, 4 Months of USCE University Hospital
Reply With Quote Quick reply to this message



Reply

Tags
Biochemistry-, Immunology-, Step-1-Questions

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Medical School
Choose "---" if you don't want to tell. AMG for US & Canadian medical schools. IMG for all other medical schools.
USMLE Steps History
What steps finished! Example: 1+CK+CS+3 = Passed Step 1, Step 2 CK, Step 2 CS, and Step 3.

Choose "---" if you don't want to tell.

Favorite USMLE Books
What USMLE books you really think are useful. Leave blank if you don't want to tell.
Location
Where you live. Leave blank if you don't want to tell.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Endocarditis and peripheral embolization! m82_ghasemi USMLE Step 1 Forum 8 09-24-2011 09:55 PM
peripheral capillary vasoconstriction chienpolska USMLE Step 1 Forum 0 08-18-2011 09:11 PM
Conduct Disorder Vz Antisocial Personality Disorder Ayshee USMLE Step 2 CK Mnemonics 1 10-30-2010 11:33 AM
The difference between Conduct Disorder and Oppositional Defiant Disorder Telsa-Farad USMLE Step 2 CK Forum 2 06-15-2010 03:08 PM
Delusional Disorder or Brief Pshychotic Disorder obgynaim USMLE Step 1 Forum 1 12-20-2009 09:06 AM

RSS Feed
Find Us on Facebook
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

USMLE® & other trade marks belong to their respective owners, read full disclaimer
USMLE Forums created under Creative Commons 3.0 License. (2009-2014)