I am not a specialist, though I have spent all my adult life in studying, under all possible profiles the problems of mind, emotions, and psychological suffering. I have reached the conclusion that there is a great deal of overlapping between syndromes and that, perhaps, it's not that important to know the precise location of each case in the many definitions. It is important to know everything possible, in order to find the strategies to cope with problems, but I think this should be made not so much having in mind the abstract classifications but rather the concrete cases.
Syndromes may be made more serious by the history of the persons. I believe that neurons are more important that traumas (bad parenting, for example). But the merging of the two kind of causes should always be taken in account and each individual history is probably so complex that it should be studied and interpreted in relation to all the causes involved. Fast driving may result in an accident, but there may be also bad sight, faulty brakes, limited visibility and so on.
A defective mirror neuron is very likely to make empathy more difficult. But what if the person has also been subject to bullying, violence, difficult environments? The propensity to be gentle and kind has certainly a genetic root, but often the equilibrium between being good, norm abiding, supportive of others and being the opposite, may be precarious and can be shifted one way or the other by the weight of an hair.