Billy Step 1 Questions # 96 - 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 01-10-2013
billy's Avatar
USMLE Forums Guru
 
Steps History: Not yet
Posts: 444
Threads: 109
Thanked 369 Times in 208 Posts
Reputation: 379
Arrow Billy Step 1 Questions # 96

A 46, XY infant is born with a nonsense mutation in the SRY gene. Which of the following will be the symptomatic manifestation of this mutation?

(A) Female phenotype
(B) Female pseudohermaphrodite
(C) Male phenotype
(D) Male pseudohermaphrodite
(E) True hermaphrodite
Reply With Quote Quick reply to this message



  #2  
Old 01-10-2013
USMLE Forums Scout
 
Steps History: Not yet
Posts: 57
Threads: 13
Thanked 17 Times in 15 Posts
Reputation: 27
Default

e true hermo
Reply With Quote Quick reply to this message
  #3  
Old 01-10-2013
USMLE Forums Guru
 
Steps History: Not yet
Posts: 375
Threads: 17
Thanked 131 Times in 81 Posts
Reputation: 147
Default

No clue...Can someone plz explain this...Thanks
Reply With Quote Quick reply to this message
 
  #4  
Old 01-10-2013
USMLE Forums Veteran
 
Steps History: Step 1 Only
Posts: 283
Threads: 35
Thanked 206 Times in 115 Posts
Reputation: 216
Default

Quote:
Originally Posted by billy View Post
A 46, XY infant is born with a nonsense mutation in the SRY gene. Which of the following will be the symptomatic manifestation of this mutation?

(A) Female phenotype
(B) Female pseudohermaphrodite
(C) Male phenotype
(D) Male pseudohermaphrodite
(E) True hermaphrodite

I will go for A - Female phenotype. I remember MD 1 embryo guy was saying mutation of SRY gene will make you look like a girl to the rest of the world. I will check it out.
Reply With Quote Quick reply to this message
  #5  
Old 01-10-2013
USMLE Forums Scout
 
Steps History: Not yet
Posts: 24
Threads: 2
Thanked 4 Times in 4 Posts
Reputation: 14
Default

will go for D.
Reply With Quote Quick reply to this message
  #6  
Old 01-11-2013
fat1iscool's Avatar
USMLE Forums Guru
 
Steps History: 1+CK+CS
Posts: 399
Threads: 45
Thanked 147 Times in 94 Posts
Reputation: 157
Default A

(A) Female phenotype
Reply With Quote Quick reply to this message
  #7  
Old 01-11-2013
neha_subh's Avatar
USMLE Forums Veteran
 
Steps History: 1 + CS
Posts: 209
Threads: 18
Thanked 112 Times in 75 Posts
Reputation: 122
Default

A 46, XY infant is born with a nonsense mutation in the SRY gene. Which of the following will be the symptomatic manifestation of this mutation?

(A) Female phenotype
__________________
lets kick some doors open and help each other to reach our destinies
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message
The above post was thanked by:
Doctor Ali (01-11-2013)
  #8  
Old 01-11-2013
neha_subh's Avatar
USMLE Forums Veteran
 
Steps History: 1 + CS
Posts: 209
Threads: 18
Thanked 112 Times in 75 Posts
Reputation: 122
Default

Quote:
Originally Posted by neha_subh View Post
A 46, XY infant is born with a nonsense mutation in the SRY gene. Which of the following will be the symptomatic manifestation of this mutation?

(A) Female phenotype
and in these patients dopamine related diseases like schizophrenia and parkinsons diseases are common because SRY-gene makes a protein that controls the dopamine concentration..
__________________
lets kick some doors open and help each other to reach our destinies
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message
The above post was thanked by:
Doctor Ali (01-11-2013), fat1iscool (01-12-2013)
  #9  
Old 01-11-2013
nandish_m's Avatar
USMLE Forums Addict
 
Steps History: Not yet
Posts: 117
Threads: 5
Thanked 59 Times in 40 Posts
Reputation: 69
Default

Quote:
Originally Posted by Doc4Step1 View Post
No clue...Can someone plz explain this...Thanks
normally SRY gene on Y chromosome responsible for testis devpt

non sense mutation of sry gene ---> absent testis ---> no leydig/sertoli cells.

absent leydig cell---> absent male internal/external genitals (no testosterone
,DHT)

absent sertoli cells ---> MIF absent ---> Mullerian duct devlops --> female internal structures develops..

so patient is phenotypically female, genotypically male(XY)
Reply With Quote Quick reply to this message
The above post was thanked by:
Doctor Ali (01-11-2013), dr mumble (06-18-2013), zeal7 (01-11-2013)
  #10  
Old 01-11-2013
billy's Avatar
USMLE Forums Guru
 
Steps History: Not yet
Posts: 444
Threads: 109
Thanked 369 Times in 208 Posts
Reputation: 379
Correct Answer A is correct

Without a functional sex-determining region of the Y chromosome (SRY) gene, no symptoms will be noticed, and the embryo will develop as a phenotypical female. Normally, the SRY gene encodes the testis- determining factor (TDF), which is responsible for the differentiation of the indifferent gonads into testes. In the testes, Leydig cells produce testosterone and Sertoli cells produce müllerian-inhibiting substance (MIS). Testosterone causes the development of the mesonephric (wolffian) duct into male internal sex
organs (remember the mnemonic SEED: Seminal vesicles, Epididymis, Ejaculatory duct, and Ductus deferens), and the development of male external organs after conversion to 5-hydroxytestosterone. MIS causes regression
of the paramesonephric (müllerian) duct, preventing development of female organs. In the absence of TDF, whether due to a destructive mutation of SRY or to a normal 46,XX karyotype, the wolffi an duct regresses spontaneously;
the müllerian duct develops into the fallopian tubes, uterus, and upper vagina; and the external genitalia feminize. This condition will likely be discovered incidentally if a karyotype is performed for an unrelated reason.
Reply With Quote Quick reply to this message
The above post was thanked by:
Asra Nayab (01-12-2013), Doctor Ali (01-11-2013), dr.rick (03-28-2013), nandish_m (01-11-2013), neha_subh (01-12-2013), zeal7 (01-11-2013)
  #11  
Old 01-11-2013
USMLE Forums Scout
 
Steps History: Not yet
Posts: 44
Threads: 9
Thanked 6 Times in 5 Posts
Reputation: 16
Default

1st I thought true herm but female phenotype is rt
Reply With Quote Quick reply to this message
  #12  
Old 01-11-2013
USMLE Forums Veteran
 
Steps History: Step 1 Only
Posts: 283
Threads: 35
Thanked 206 Times in 115 Posts
Reputation: 216
Default

It's Swyer syndrome that I was thinking about in my pervious post.




Let's look at the question again. We 46 XY and a mutation in SRY gene. So genetically we got 46 XY which is a male infant by a common sense. Problem arises when the same individual has mutation in SRY gene. What that does us?



Normally SRY gene will differentiate into testes. From there, Sertoli cells and Leydig cells are formed and proceeds further. When there's a mutation/problem in SRY gene, the gene will not differentiate into testes.



Swyer syndrome/XY gonadal dysgenesis is type of hypogonadism in person whose karyotype is 46,XY. People with this disorder will have female external genitalia, a normal uterus and fallopian tubes. However, they do not have functional gonads (ovaries/testes). Instead, they have undeveloped clumps of tissue called streak gonads. So, people with Swyer syndrome are typically raised as females and have a female gender identity.



To make a simpler:



Girls with Swyer syndrome will have XY chromosomal makeup as boys instead of XX chromosomal makeup. Despite having the XY chromosomal makeup, these girls with Swyer syndrome look female and have functional female genitalia, vagina, uterus and fallopian tubes. However, they do not have ovaries. They have streak gonads and therefore, will not undergo puberty.




So the answer is A.
Reply With Quote Quick reply to this message
The above post was thanked by:
Janakpriya (01-13-2013), nandish_m (01-11-2013), neha_subh (01-12-2013)
  #13  
Old 01-13-2013
Janakpriya's Avatar
USMLE Forums Addict
 
Steps History: Step 1 Only
Posts: 101
Threads: 9
Thanked 47 Times in 30 Posts
Reputation: 57
Send a message via Skype™ to Janakpriya
Default

Female phenotype.. Ans A..
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message



Reply

Tags
Genetics-, Step-1-Questions, Syndromes-Acronyms

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
Billy Step 1 Questions # 84 billy USMLE Step 1 Forum 8 11-18-2012 05:26 AM
Billy Step 1 Questions # 83 billy USMLE Step 1 Forum 4 11-18-2012 12:20 AM
Billy Step 1 Questions # 49 billy USMLE Step 1 Forum 7 10-28-2012 10:06 AM
Billy Step 1 Questions # 33 billy USMLE Step 1 Forum 6 10-18-2012 10:17 AM
Billy Step 1 Questions #4 billy USMLE Step 1 Forum 3 10-02-2012 08:49 PM

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)