Or is it a cause that manifests as other things, like obsessive-compulsive disorder, dependency, and paranoia?

Also, how does one deal with it?

Low self-esteem is a result of something that happened to you during childhood. Most of the time it can be traced back to when someone berated you all the time, didn’t give you deserved credit for things done, or just being ingnored, feeling like you never belonged. There are several steps one can take to try to overcome this, one of the easier ones and most of the time the first step is to just look in the mirror and tell the person you see there that you love them, aloud. Say it several times. Do it for several weeks. One other way is to make up your own validation cards which say I am good at…, or I am like because I….., all the good things you can think of that describe yourself. Read those cards aloud to yourself for a couple of weeks also, it will be a starting point for any other work you do.