Good question. I am studying their work on capitalism and schizophrenia right now. This is for an introduction to an essay collection. I am not aware of any direct connection to post-humanism, but I suppose inferential connections may be constructed.

So far discussions on schizophrenia have inhabited a medical dimension only, with alarmingly poor results limited, as they have always been, to the suppression of symptoms. Psychiatry does not do abstract. It doesn't think to think beyond the next drug. It is possible that the illness represents the internalisation of negative aspects of the world without filters. Years ago people did immense work on the subject (see film The Ruling Class that dealt with shifting identities) but now it is once again the medical model that produces the same old genes, neurones and drugs mantra scoured from experiments on existential rodents.

Technically they aren't related, though some scholars have attempted to use D&G to develop ideas of posthumanism. Schizophrenia for D&G is the social condition/mental condition/enviornmental condition of contemporary capitalism. Paranoia isn't a part of their theory as far as I recall, I think guattari deals with paranoia a bit, but it is as a social condition.