Hello Rajeevkiit, I think the answer is Nobody knows! But there are PNH support groups that can help you to understand better than I can. Try getting in touch with--
http://www.aamds.org/about/pnh You can probably get some good support and good answers.
Please don't scare yourself. There are good medicines that can help people live a long life and the doctors are learning better ways to treat these illnesses. Please get in touch with AAMDS as soon as you can.
I'm sure there are others here who can tell you how to get in touch with a PNH group too.
Take care and be hopeful