check the global group memeberships of alogged in user

Hi All,
I'm developing an internal website for my clint. Some of the components in a web page should be made available only if the user is a prat of certain groups.
Can any one please tell me how to get the global membership groups a user is part of or a method to check if the user is a part  of certain groups ?
kindly help. I'm using c# as  my programming language.
 
Thanks,
Suneel k R
 
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