GC holder (minor) travelling out of US for more than 6 months

[kal_amd]

Hi,

I have received my GC (employment based) in early 2009 and my family members (wife and my son) also received their GC along with me.

This year my wife and my son travelled to India in May'2011. Now my wife is planning to come back next month but planning to leave my son in India for the next 2 years and bring him back in 2013 when I will be eligible to apply for my citizenship. Will my son lost his GC status if he is out of US for 2 years even though he visits US for a month couple of times in a year? Will he get US citizenship when I apply for citizenship in another 2 years?

If I want to make sure he doesnt become ineligible for US citizenship what do I need to do? Please suggest.