Calculating the risk of cleft palate for these parents - 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 05-27-2011
Amenah's Avatar
USMLE Forums Addict
 
Steps History: 1+CK+CS
Posts: 160
Threads: 15
Thanked 77 Times in 57 Posts
Reputation: 88
Genetics Calculating the risk of cleft palate for these parents

A male new born at 39 wks gestation has a unilateral cleft lip and palate. studies shown that concordance for this trait in MZ twins 0.40 and DZ twins 0.04. the incidence of cleft lip and palate in general population is 0.001 if the parents of this newborn have a second child the risk for unilateral cleft lip and palate in this child is approximately which?

A) 75%
B) 50%
C) 25%
D) 4%
E) 0%

hi guys iv got this Q and i need ur help in approaching the correct answer
Reply With Quote Quick reply to this message
The above post was thanked by:
bebix (05-28-2011), Claus_CU (05-28-2011), Hamada (09-30-2014)



  #2  
Old 05-27-2011
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,175
Threads: 38
Thanked 854 Times in 478 Posts
Reputation: 864
Default

Assuming the parents dont have twins (can't really calculate I think), it would be comparing to the General Population where incidence is 1/1000.

I would go with D) 4%

I have no idea!
Reply With Quote Quick reply to this message
  #3  
Old 05-28-2011
bebix's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,357
Threads: 194
Thanked 3,268 Times in 881 Posts
Reputation: 3278
Default

Quote:
Originally Posted by patelMD View Post
Assuming the parents dont have twins (can't really calculate I think), it would be comparing to the General Population where incidence is 1/1000.

I would go with D) 4%

I have no idea!
My answer is also 4%, but I didnīt used the general population incidence.
Since the concordance for this trait in DZ twins is 0.04, this should also be for a future child...so I multiplied 0.04*100%...
Reply With Quote Quick reply to this message
The above post was thanked by:
Claus_CU (05-28-2011)
 
  #4  
Old 05-28-2011
USMLE Forums Veteran
 
Steps History: Not yet
Posts: 219
Threads: 18
Thanked 159 Times in 81 Posts
Reputation: 158
Default

Quote:
Originally Posted by bebix View Post
My answer is also 4%, but I didnīt used the general population incidence.
Since the concordance for this trait in DZ twins is 0.04, this should also be for a future child...so I multiplied 0.04*100%...
Exactly what I did, however i'm still not sure abt the answer..
Reply With Quote Quick reply to this message
  #5  
Old 05-28-2011
bebix's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,357
Threads: 194
Thanked 3,268 Times in 881 Posts
Reputation: 3278
Default

Quote:
Originally Posted by Amenah View Post
A male new born at 39 wks gestation has a unilateral cleft lip and palate. studies shown that concordance for this trait in MZ twins 0.40 and DZ twins 0.04. the incidence of cleft lip and palate in general population is 0.001 if the parents of this newborn have a second child the risk for unilateral cleft lip and palate in this child is approximately which?

A)75%
B)50%
C)25%
D)4%
E)0%

hi guys iv got this Q and i need ur help in approaching the correct answer
are we close?
Reply With Quote Quick reply to this message
  #6  
Old 05-28-2011
Amenah's Avatar
USMLE Forums Addict
 
Steps History: 1+CK+CS
Posts: 160
Threads: 15
Thanked 77 Times in 57 Posts
Reputation: 88
Default

hi guys ...thanks ....i took this question from kaplan q bank and the correct one is 4% ...u r totally correct ,i read the explanation but i didn't get how to approach the correct answer!!!
so we assume that the child would be DZ and we took 100% the general population and multiply 0.04 by 100% ...right?
thanks again
Reply With Quote Quick reply to this message
  #7  
Old 05-28-2011
bebix's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,357
Threads: 194
Thanked 3,268 Times in 881 Posts
Reputation: 3278
Default

Quote:
Originally Posted by Amenah View Post
hi guys ...thanks ....i took this question from kaplan q bank and the correct one is 4% ...u r totally correct ,i read the explanation but i didn't get how to approach the correct answer!!!
so we assume that the child would be DZ and we took 100% the general population and multiply 0.04 by 100% ...right?
thanks again
Yes..."genetically speaking", DZ twin are "just" two different sibling
Reply With Quote Quick reply to this message
The above post was thanked by:
Amenah (05-28-2011)
  #8  
Old 05-28-2011
Amenah's Avatar
USMLE Forums Addict
 
Steps History: 1+CK+CS
Posts: 160
Threads: 15
Thanked 77 Times in 57 Posts
Reputation: 88
Default

Quote:
Originally Posted by bebix View Post
Yes..."genetically speaking", DZ twin are "just" two different sibling
Okay can i know why we didn't use the incidence which is 0.001 and we assume 100% for the general population. thank you again
Reply With Quote Quick reply to this message
  #9  
Old 05-28-2011
bebix's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,357
Threads: 194
Thanked 3,268 Times in 881 Posts
Reputation: 3278
Default

Quote:
Originally Posted by Amenah View Post
Okay can i know why we didn't use the incidence which is 0.001 and we assume 100% for the general population. thank you again
100% is not the general population...100% is just to convert 0.04 to percent.
I didnīt use the general population incidence of 1/1000, because this qs. is about a particular family which already have a child with unilateral cleft lip.
Reply With Quote Quick reply to this message
  #10  
Old 05-28-2011
Amenah's Avatar
USMLE Forums Addict
 
Steps History: 1+CK+CS
Posts: 160
Threads: 15
Thanked 77 Times in 57 Posts
Reputation: 88
Thumbs Up

Quote:
Originally Posted by bebix View Post
100% is not the general population...100% is just to convert 0.04 to percent.
I didnīt use the general population incidence of 1/1000, because this qs. is about a particular family which already have a child with unilateral cleft lip.
ha Okay i got it ,we just assume it's a DZ and pick the 4% ...thanks Bebix .
Reply With Quote Quick reply to this message
  #11  
Old 05-28-2011
bebix's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,357
Threads: 194
Thanked 3,268 Times in 881 Posts
Reputation: 3278
Default

Quote:
Originally Posted by Amenah View Post
ha Okay i got it ,we just assume it's a DZ and pick the 4% ...thanks Bebix .
Yes, in this particular question weīre assuming that the risk does not change if you are a DZ twin or a singleton.
The risk within the pair of DZ twin should be equal to the risk between two brothers.
Reply With Quote Quick reply to this message
The above post was thanked by:
Claus_CU (05-28-2011)
  #12  
Old 05-28-2011
USMLE Forums Veteran
 
Steps History: Not yet
Posts: 219
Threads: 18
Thanked 159 Times in 81 Posts
Reputation: 158
Default

Wow. You guys are seriously good with genetics.
Reply With Quote Quick reply to this message



Reply

Tags
Genetics-, 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
Genetic Counseling of CF Parents Claus_CU USMLE Step 1 Forum 19 07-24-2011 04:40 AM
Cleft Lip/Palate apx85 USMLE Step 1 Forum 1 03-16-2011 04:41 PM
Anterior versus Posterior Cleft Palate schiwei USMLE Step 1 Forum 1 12-28-2010 02:39 PM
cleft palate, microcephaly, and midface hypoplasia khushboo USMLE Step 1 Forum 10 09-24-2010 07:57 AM
Calculating the Pulmonary Vascular Resistance! doctorF USMLE Step 1 Forum 3 07-12-2010 02:04 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)