The violence could also stem from frustration/anger at being different or feeling a certain way and not understanding it. A lot of conditions don't have violence as an inherent symptom, but rage stemming from frustration and confusion I'd say is pretty common with a lot of diagnoses revolving around the brain and nervous system. With children especially, the ability to cope with that rage is probably far less than an adult.
I hope the kid gets help and gets better. The mom sounds pretty clueless though-- some people don't get that just because you hold your kid responsible doesn't mean you hate your kid or should beat them or whatever, just that you recognize where the problem is coming from >.<