They found another gene variant in autists and mentally impaired patients. In some, it was also found in a parent, and in others, it was a new mutation. It has to do with how synapses operate. Another step in understanding and then, one day, ameliorating the problems.
Since the allele is associated with retardation and autism (but not necessarily at the same time, since some autists with it are normal intelligence), it brings to mind what I wrote about yesterday, that sometimes it makes sense to categorize mental health problems by their biological symptoms rather than their psychological ones. The subjects in this study could be categorized as autistic and/or retarded, or they could be categorized as having a synapse problem (or something like that). It could also be that the symptoms are related to the part of the brain the allele is expressed in.